1980s/90s Cadillac On Board Diagnostics & Malaise Era Fun

Watch for some details on how to check the codes and step through engine parameters on 80s/90s era Cadillacs.

[@votingcitizen]

Fantastic Seville interior. The max flat dash. Real memory skills to remember those diagnostics.

[@Luke-PlanesTrainsDogsnCars]

Horse's for courses of course ... But this was part of the malaise era, the dash looked as though the designers drew nothing but hi-fi components and Frigidaires. A buttoned sofa as a drivers seat ..really? It says more about American taste than automotive design.

[@stevevarholy2011]

I kept hearing Mr. Regular say "Brown" over and and over in my head. My uncle had a beautiful bustleback Seville with the Black/Silver Two-Tone. The dash in the Seville is very similar to the very handsome one that our 1984 Sedan DeVille had. The Sedan DeVille was a beautiful car that had a tragically fragile transmission.

[@Sedan57Chevy]

These have the absolute best door chime ever! Love seeing some Malaise love! Glad you caught the leaky Merc before something bad happened. I always forget how nice these Sevilles actually are. Aside from the 4100 they're top level cars.

[@buckykattnj]

Interesting to see a bustleback Seville in nice shape... a far cry from the 4x4 Seville being featured on Junkyard Digs lately. It was never one of my favorite designs, but it does bring back some memories, as my aunt and uncle had one brand new (I think a 1980) that me and my cousin got ferried back and forth up and down the east coast. in it.. twice. Very nice car at the time, and it was cool when my uncle used the CB to banter with traffic. That computer system is pretty neat... I am fairly GM-knowledgeable, and didn't know about that one... it's a far cry from using a paper clip and counting blinks.

[@khakiswag]

That is GM’s Computer Command Control system. It seems simple now but back then it was the most advanced computer used in a car. GM literally created the “Check Engine” light. CCC was created to detect a problem before it completely failed by sensing deteriorating performance. Then assist in repair by telling the technician where to start looking. It became OBD1 then later OBD2 that we use today, all based on CCC. For all their problems GM was a very innovative company at one time.

[@NFSMAN50]

The Bustleback Sevilles lol. Very interesting style in the 80s. I was interested with this car style a few years ago lol. I always liked the interior

[@timw8228]

A co-worker asked me if the seller of mine paid me to come and get it.... some people have no class... lol

[@analogidc1394]

One thing that stands out on older cars is their clean simple dashboards in comparison to today. Cars with the larger than life touch screen in the center always make think of a giant smart phone that's been glued to the dash.

[@Luke-PlanesTrainsDogsnCars]

Akk ..I'm not sure a dash designed like randomly stacked hi-fi equipment inside a Frigidaire was a good look either.

[@douglasb.1203]

Opinions are like a**holes, everyone has one. The early '80's land yachts had high end materials to touch and brought technology to the forefront. The Delco/Bose stereo system has such fantastic speakers all the car needs is a new head unit with CD & Bluetooth. Fantastic baroque interior.

[@billiebobbienorton2556]

Another thing that stands out when its cold out is a woman with three nipples.

[@jdwxflyer]

Brings back good memories of my dad’s ‘79 ElDorado. These bustleback Sevilles were all the rage in our neighborhood but I always thought the El Dorado was sportier and frankly better looking. The diesel under the hood was its downfall. Thanks Adam!

[@johncarroll1403]

Boy, not many of those Sevilles survived, and certainly not in that condition! Another gem! Thanks Adam!

[@rossharris94501]

Oh man! I could practically smell the Seville interior. I love the quiet rushing sound of the engine rev. during the demonstration of the RPM's. Another nice video.

[@gregdelagrange8573]

You have a very nice collection of automobiles. I definitely know what kind of mileage you get with the HT4100. Tip, I use high pressure fuel injection hose for the fuel filter connector on my Fords. Less susceptible to splitting due to more layers and binding inside. You're right about checking them often.

[@georgefrancis3067]

... .

[@slicksnewonenow]

Plus One for using fuel injection hose! Never fails...

[@johna.4334]

@George ???

[@michaelorlando6159]

Me too i only keep fuel injection hose in the shop so i dont accidentally use carb hoses on a fuel injection car. Plus as you said the extra reinforcement avoids the splitting

[@rafranks1410]

Due to ethanol?

[@garyvisser8987]

Did not remember that diagnostic system on those cars. Never worked to the dealership but always help the little old ladies with their cars. Cheers. Subscribed!

[@OBC-radio]

I’d like to see a video on that Olds. My parents had lighter blue version, and that’s the first car of theirs I remember. The 80s/early 90s cars will soon have their day!

[@steveh9869]

Wow what a beautiful collection of pristine vehicles. Please keep making these videos! They’re fantastic!

[@alreynolds7152]

I would still drive that caddy today those interiors make you feel like a King 👑 !

[@rafranks1410]

Slowly burning through a tank of gas. The struggle is real… If I lived closer, I’d volunteer to help! Thanks for sharing.

[@ZGryphon]

Nifty. My grandparents had one of those hunchbacked Sevilles. My grandmother absolutely loved it. My grandfather... not so much, but Gram's word was law on these matters. :)

[@DSP1968]

I don't recall seeing your bustleback Seville or your 98 -- both very nice! Hopefully you'll complete videos on each sometime soon. I did have a friend who bought one of those Sevilles with the Bose system new -- it was quite spectacular in a two-tone apricot metallic/something lighter and tan leather interior.

[@toronado455]

He has so many amazing cars. Those are both beautiful.

[@desertmodern7638]

Very cool to see the on board diagnostics in operation. And I love the black-trimmed dash of the final two years of this generation.

[@mdogg1604]

My '90 DeVille is the best car, overall, that I've ever owned. The 4.5 gives me 20 mpg suburban driving and can hit 30 mpg with a tail wind on the road. Owned since '93, 189K miles. If anyone doesn't believe so, let's go for a drive and pass some gas stations.

[@douglasb.1203]

Had a '94 4.9 Deville sourced out of Arizona with a coach roof and gold package. 30 plus mpg fully loaded with the air on.

[@mdogg1604]

@@douglasb.1203 The 4.5 and 4.9 were amazing engines. Lots of low-mid range torque, just where I personnaly like it.

[@douglasb.1203]

@@mdogg1604 IMHO so much better than the Northstar. Drove both (had a '93 also) to around 180,000 before selling. The '93 was incredibly reliable, the '94 not so much.

[@mdogg1604]

@@douglasb.1203Was '94 the advent of the NorthStar? Lots of problems with early NorthStars. I also have an '08 DeVille; from what I've read the cylinder head sealing problems/ crank case sealing problems have been solved by 2008, and this seems to be true with my car. And BTW, I think few people realize how well a car of the vintage of the 2008 handles because the average person is advanced in years and doesn't really DRIVE the car. It handles on hills and curves like it's glued to the road. Just my opinion.

[@douglasb.1203]

@@mdogg1604 truth on the handling. When GM went FWD on the large vehicle platform the cars gained a fully independent suspension. Cadillacs adjustable suspension was sublime, except went it bit the farm.

[@vincentgranite9481]

That car gives me chills. My dad bought a salvage Seville, "minor" under hood fire. The body work was no problem. The harness had the car tied up for so long that he patted the car out. I think it read a current model year car when bought and was about 3 years sitting before he went into inventory. Took a beating on that one

[@Rfk1966]

Pretty one. Our HT4100 averaged 32 mpg on the way back from Colorado. Granted, it was all downhill, but my cousin following behind in their Mazda GLC was doing far worse in terms of fuel economy.

[@timw8228]

Supposedly the diesel got really good mileage.

[@turnne]

@@timw8228 When the engine was still running....those diesel engines were horribly unreliable

[@timw8228]

@@turnne Yeah I remember them and test drove an Olds. Back then water in diesel seemed to be the biggest issue as I recall. Today's diesel fuel is refined better. Clickty clack clikity clack as I recall is what you could hear inside the car.

[@turnne]

@@timw8228 Mercedes has a couple of diesel engines during this time period that typically lasted for hundreds of thousands of miles. The technology was out there GM just decided to go another direction and build a high failure rate engine

[@aprules2]

Man my grand parents both had Tourback Seville's I loved them. Even though they were plagued with problems I really want one again. I remember how big that dashboard looked when I was a kid

[@fourdoorglory]

YAY to your Malaise era cars!! Have been waiting to see your ‘86, 98 Regency. Please do a complete review of this car. Driving them at the Milford proving ground provided a test driver with a very comfortable place to spend an 8 hour work day. These are very underrated/under appreciated cars.

[@weegeemike]

That Olds 98 really grabbed my attention! My first car was a 1990 Ninety Eight....great car. Bought it for $750 and drove it through high school and college. I really regret getting rid of it, was MINT when I gave it away.

[@777jones]

Those cars were indestructible.

[@Chris_Troxler]

@@777jones I was just about to say the the same thing.

[@robertriley1569]

I had an 89 eighty eight Royale Brougham. Car had problem after problem but lasted all the way up to 2012.

[@rbielarski]

Love your Seville & colors on int/ext. So luxurious & classic 80's styling.

[@OldeHadleyVintage]

Hey Adam! Love your videos soooo much! Really love your collection! I saw you had the Olds out which was great to see because it’s cousin is my absolute favorite car: 87-90 C-body Buick Electra Park Avenue! I have been searching so long for one in top notch shape… my dream is to own one. You had mentioned you have one as well? Hope to see it sometime!! Thanks for the great videos!!! Jeff 👍🏼👍🏼

[@skinnerhound2660]

Beautiful Seville, looked like 34K on the odometer, amazing. I have yet to figure out how many cars you own but one thing I know is you can only drive one at a time. Which begs the question, do you have a system for dormant lack of use? Do you use Sta-bil in the fuel tank, battery tenders on cars where they are present, what kjnd of brake fluid do you use, do you use Marvel Mystery oil, how often do you change tires, do you change coolant and hoses? I'm just really curious if you keep date records or repair as it presents. I own ten collectors in a heated garage and it is a challenge to keep systems from deteriorating. Couldn't imagine maintaining your herd. Thank you for sharing your collection, contacts and knowledge.

[@garyvisser8987]

If you drive them at least once a month 25 to 50 miles and use non-ethanol fuel you will find your maintenance cost go way down. You build enough heat in the motor to take care of the condensation that has built in the engine and transmission and then top them off with good fuel when you're done driving them every time. That's why piston/prop airplanes are always parked full of fuel. And towards the end of the trip get on them once in a while blow the cobs out so to speak!

[@skinnerhound2660]

@@garyvisser8987 I have used 92 non-ethanol in all my collectors for years, no brainer. As I stated in my comment, that is only one of many mechanical issues that need a preventative schedule or solution especially when seldom driven. Hoses, anti freeze, belts, tires, wheel cylinders, oil, ect. have a much different life when a vehicle is not routinely driven. How and where they're stored is also a factor. Most of my car friends of forty years have many cars and only drive them a couple of months in good weather, thus they sit. Adam has most likely thirty plus cars that look to be stored in a warehouse . It would be impossible to drive them all on a routine during the fair weather months in Michigan. Issues will present, how he addresses them was my question to him.

[@timw8228]

My '84 Seville has a blue velour interior. Not many were made with the tufted velour interior. Where I take my Cadillacs for service a former Cadillac service person works there that work on that era. He said Cadillac was ahead of the time by doing the on board diagnostics. Same with my 'FWD '89 Fleetwood. I can read the codes the same way. I wish my late model GMC Duramax truck had the same feature. I get an idiot service light I have to take it in to be read. I know I should get a reader. Starting with the '86 Cadillac Brougham you can read the codes by jumping 2 prongs on the ADL connection if you don't have a code reader. Not as nice as reading from a dash display code.

[@mattb.7761]

My Uncle had an 84 Seville, he had it for over 20 years. Loved that car.

[@davisjones3725]

Love those 80s Cadillac Door/Seatbelt Chime..

[@jrcars7017]

The bustleback Cadillac may not suit everyone but I think it's lovely. I wouldn't mind owning one at all.

[@billiebobbienorton2556]

You can have it. Just say that I told you it was ok. :)

[@jefferysmith3930]

Today, the Seville interior looks inviting. When I was a kid, not so much. I felt like I was sitting in a hole being in the back which made me car sick. I had a friend who’s dad had one of these. His mom had a Volvo GL. I always preferred riding in the Volvo

[@edwardpate6128]

Pretty sophisticated for the early 80's!

[@terry3193]

I really like those Seville elegante models with the stainless strip. The tufted interiors are beautiful. I also really liked that generation of Olds Ninety Eights. They had great interiors and were somewhat bullet proof.

[@pjrebordao]

That kind of on-board diagnostics display in the 80s was probably unique in the world!

[@stuartaaron613]

My uncle had a 1982 Seville with the infamous 5.7 liter diesel. The problems with his wasn't with the diesel, but almost everything else. It had electrical problems, once the automatic headlights didn't turn off. This was with the car parked in his garage, which was under the house. When he tried to start the cat the next morning, nothing. It wasn't easy pulling the car out of the garage to jump start it. Also it had problems with the transaxle leaking. The car spent most of 1982 at the dealership shop. At the end of the year he went to trade it in. His Cadillac dealer offered him very little on the trade-in (knowing that the car was a lemon). So he went to his Lincoln, and traded it towards a 1983 Mark VI sedan. He later bought 1987 and 1992 Lincoln Town Cars. He didn't go back to Cadillac until 2000 when GM was offering 0% financing (being an accountant free money wasn't something he would pass up).

[@joe6096]

The Olds 98 and Cadillac Seville. Cars of my youth. My Mom had a 1988 98 and my Grandfather had a 1985 Eldorado. I absolutely loved his Eldorado. I learned to drive on it (and Mom’s 98 too) when he handed me the keys when I was 13 in 1990 to let me back it out of the garage! Then it was stolen in 1993 and it broke my heart. I miss that car to this day.

[@ellisonhamilton3322]

That is a handsome interior.

[@stormythelowcountrykitty7147]

Agreed!

[@jameslowry4299]

I'm on the like side of the bustleback Seville divide, somebody on my paper route had one when I was a kid and I thought it was cool as hell. Love that era Cadillac interior, I had an Eldo with the HT4100, it wasn't fast but otherwise a very satisfying car.

[@mattcrooke8321]

That has to be the best door chime I have ever heard!!!

[@matt8151]

Wow would love to see more about that Olds 98

[@OldeHadleyVintage]

Yes me too! I actually am a HUGE fan of the C Body Buick Electra Park Avenues myself and been looking for a 1990… ugh would be a dream come true… like riding on a cloud!

[@OldeHadleyVintage]

For some reason Adam never replies to any of these… kinda upsetting 😔

[@chadsmith412]

Adam, how do you prevent flat spots on tires when your cars that are not driven for months?

[@AlessandroCorazzaCA]

I'm not Adam (obviously) but I park on pieces of rigid foam insulation for up to 7 months and have had no problems.

[@chadsmith412]

@@AlessandroCorazzaCA Can you send a link of what insulation you are talking about? Is this something you buy at Home Depot?

[@AlessandroCorazzaCA]

@@chadsmith412 Yes you can, I use the pink foam that's about 1" thick and cut it into smaller pieces to fit under the tires.

[@jetsons101]

Must say Adam, you have a nice back yard.... Thanks for posting.....

[@OLDS98]

The video was informative. My 1992 Oldsmobile Toronado has on board diagnostics. I like the fact GM did that. Your Seville is nice. It is loaded too! I saw your downsized Ninety Eight too. I have a 1996 Ninety Eight too. It was the last year. It would be nice to see you share your Ninety Eight. Thank you for sharing.

[@howebrad4601]

Love your 80s stuff too! I also own an x car and a 91 Cadillac deville which is a C car

[@The_R-n-I_Guy]

My 1996 Buick Roadmaster sedan has similar hvac diagnostic codes. Same off and warmer button to access it. Since it's obd2 there are a bit of difference in functionality. But still a cool feature

[@garyruark9506]

I think the bustleback Sevilles are fantastic. The greatest of GM thumbing its nose at everyone. And they sold too!!! I would drive that car anytime. At least on weekends.

[@neilouellette3004]

I had a mint 1983 Fleetwood Brougham D'Elegance Coup HT4100 Black w/Red leather back in 1987. Never had a problem w/my diagnostics but that HT 4.1 was junk. I only had 31,000 miles on it and broke down once a week. We called it Hook & Tow 4100. You couldn't even pass anyone on the Interstate w/a good runnin' HT4100. No diagnostic problems w/my 83 Fleetwood D'Elegance at all.

[@dave1956]

The newer Cadillac’s were no better. I remember a 2004 Seville coming into our shop for an unrelated problem and we discovered that the fuel rail was spraying gas everywhere. The woman that owned it thought that we were trying to rip her off. Once we showed her what was going on, she apologized.

[@DannyKoKo]

Such a lucky man to have these vehicles

[@courtneypuzzo2502]

the Caddy in the thumb nail pic is a Bustle Back Seville which was the 2nd gen 1980 to 1985 Model years

[@stymemcquarn893]

We call em slant backs down here. 💪🏾

[@HypocriticYT]

Many years ago after storring my 53 Cadillac coupe upon startup one tailpipe had no exhaust escaping. Took it to two muffler shops and both had no idea. I later took it to the mechanic Ken Lowry who redid the engine and he found a mouse nest had blocked the pipe.

[@charlie_nolan]

I love the interior design!

[@terribelbliss9646]

That is one of the positives of cars of that era, they’re good on gas. 😉👍

[@kc0lif]

i like the bustleback Seville.

[@christopherkraft1327]

Your Seville is very luxurious, it looks like it's an Elegante??? 👍👍🙂

[@RareClassicCars]

Nope. Standard model

[@christopherkraft1327]

@@RareClassicCars it certainly is beautiful!!

[@ellisonhamilton3322]

@@RareClassicCars Sweet interior.

[@3713msg]

1981 Cadillac with the 368 8-6-4 also have the on board diagnostics. In fact, one can lock in the engine to "8" "6" or "4" on the heater control. I worked at the Cadillac Dealer in the 1980's as service manager. We had horrible problems with the diesels, the HT-4100, and most everything on the Deville FWD cars. They were just horrible cars, and we lost many lifelong customers because of these poor quality cars and General Motors arrogance. Cadillac was under the assumption that their customers would purchase anything, no matter how bed it was, just because it said "Cadillac" on it. They found out otherwise......

[@andrerossato5846]

Beautiful cars

[@wilcoautomotive545]

I'm sure you're running non-alcohol recreational fuel. Be sure to use rubber fuel line that is rated for fuel injection. It has an internal liner that will hold fuel pressure even if the outer layer cracks.

[@V8_screw_electric_cars]

Old Cadillacs are the only cool front wheel drive cars to me because they have the flat floor which was really cool with bench seat.

[@everettcarlson3412]

With my 80s Ford, you have to cross computer module wires under the hood and then count the flashes and sequences of the check engine light to diagnose codes.

[@slicksnewonenow]

From all of the different locations you've been filming, it surely does look like you're running out of places to hide the bodies... For lack of a better term. I'm surprised that you can't buy a giant warehouse somewhere in Detroit for about $75.00.... it seems like so many of those buildings are empty there, and have been for many years. Cheers... Keep 'em coming!

[@regsmith7604]

How long do you keep the oil in the Merc?

[@toronado455]

Would it also be possible to drain/siphon the Seville fuel tank instead of burning it? That's an absolutely beautiful Seville.

[@somersetdc]

Wonderful Cadillac!!

[@michaelcoffey7362]

A friend of ours had a Bustle back Cadillac 😀 in the early 1980s

[@miketresham4783]

The blue Oldsmobile is very nice.

[@patcallahan2278]

i just got a 90 with only 24k i searched high and low for an electra and couldnt find one so i settled for this 98. they are great cars.

[@patcallahan2278]

id love to see a video of that olds 98

[@lrich8181]

Try using Marvel Mystery Oil for your fuel stabilizer,helps to keep your gas from going bad.

[@AB-pl1ko]

Adam, given that many of your cars sit will sit for extended periods. do you use ethanol free gasoline or standard blended gasoline with a fuel stabilizer in them?

[@wilcoautomotive545]

You may look around if you can get fuel from a co-op or form Farm Supply provider they sell 90 Plus which is non-alcohol 90 plus octane Plus preservative and the fuel will last many years. Not as good as aviation fuel but for catalytic converter vehicles it's a great alternative.

[@SuperCommando60]

that is one good looking interior. looks like a gentlemen's club, and not the american kind.

[@stevem.1853]

Did GM design a scan tool for the dealerships to use or was this the only way to interface with the diagnostics?

[@freddyhollingsworth5945]

01:45, I will try this on my 1983 Cadillac Deville Diesel.....I am assuming this works on the diesel cars as well? Great video, all beautiful cars!!!!

[@RareClassicCars]

It does not. No ECM

[@lordapophis7438]

Perfect car for these days! What's the fuel economy like in this one?

[@RareClassicCars]

23-25 Highway

[@lordapophis7438]

@@RareClassicCars Not bad for a Cadillac! Can I have this one?

[@jasonfarnsworth5880]

It’s super nice car brother

[@douglasthrelfall5318]

Didn’t the digital climate control have diagnostics as well? I remember having a AC Delco manual for the glossary of codes. AC Delco had blue soft cover diagnostic manuals the were generic GM & not brand specific. One I remember using was for diagnosing the wipers/washers/delay faults. I used that to install intermittent wipers in my 1973 Grand Am using all GM/AC Delco factory parts. (delay wipers didn’t come out until the 1975 model year for the A & A special bodies.

[@ghall7763]

It would be cool if you did a full Fleet video

[@taylorsutherland6973]

Gates Barrior fuel line holds up very well. Much longer lasting.

[@garymotley8196]

Love that Seville !

[@robbkiker6861]

Instead of burning the entire tank of fuel could you burn a percentage (50%) then add fresh fuel with a fuel conditioner for the remaining old gas?

[@douglasthrelfall5318]

The current (2000-2011 era) DeVille & DTS have really extensive dashboard diagnostics. Gives you status of EVERYTHING on those cars. This way, when that Northstar really does puke it’s head gaskets, you have a preview…. Ask me how I know this.

[@Dog.soldier1950]

Do you use non-ethanol fuel and/or fuel preservatives?

[@stevebyrne4235]

Cool car, thanks; looks like DDEC I/II

[@bestpilot98]

I really miss that warning chime sound!

[@paularcher4607]

I used to sell those Olds 98's back in that period. Waiting for a vid on this one. You don't have a Touring Sedan by any chance do you?😁

[@RareClassicCars]

Unfortunately not

[@klwthe3rd]

What year was that Seville? 82? 83? 84? 85?

[@RareClassicCars]

84

[@chrislemaster2695]

My friend had a 1985 Seville that had the Oldsmobile 307 CID 5.0:L V-8

[@christopherbero3388]

When do we get to see your Trans Am?

[@jaspal666]

Did Audi use this system on their 80’s 5000? I recall my ‘88 5000 Quattro had similar access to diagnostics. Edit: I did some research... seems the Audi unit used some GM components but was not a direct replacement.

[@RareClassicCars]

Not quite

[@davef.2811]

I'll never forget how many people were so disappointed in those 4100-powered cars, a common complaint being "this car is so underpowered it's almost dangerous!" Or, "It can't get out of its own way!" Cadillac lost a lot of market share and loyal customers with that one.

[@patcallahan2278]

the 4100 in the rwd cars and the e body up to 85 was just aweful....worked at a olds cadillac dealer and have driven and worked on a bunch of them. it was so pitiful that gm upgraded it with a carbed 307 lmao. the 307 was pretty underpowered too but was at least reliable. these engines along with 2.14 rear gears or whatever really made these cars much slower than they really needed to be to keep with c.a.f.e requlations.

[@davef.2811]

@@patcallahan2278 Yes, I remember my then boss's wife got rid of the 4100-powered SDeV and replaced it with one that had a 5.0 Ltr. V8 and a Rochester 4 bbl carb. Big improvement.

[@markbehr88]

I had a 81 Seville. I would like to get a 1980 model Elegante.

[@ICECREAMAN1701]

I like the 80's Seville!!!

[@kevin122759]

I would love to see a video on that X body.

[@OnkelPHMagee]

He did a couple many months ago. Do a search within the channel. I remember because that was around the time that I started to watch.

[@BullRunRoad30]

This is the first time I ever heard the words Malaise Era and Fun in the same sentence. Nice cars, though.

[@HerkkaW123]

How many cars do you own?

[@jakobschoen6499]

I love the Seville.

[@r.s.7462]

That code display is slick. Are Cadillacs the only brand that had that? Seems odd besides. You'd figure a DIY brand (e.g. Chevy) owner would make better use of it. I would think most Cadillac owners would never bother.

[@RareClassicCars]

Nope. It was on some other brands too.

[@kc9scott]

My ‘85 Chrysler Laser had a system where you cycle the ignition switch on and off 3 times (without actually starting the engine), then leave it on. After that, it flashes the code on one of the indicator lights. You just count the flashes.

[@stevevarholy2011]

The auto climate (which included the diagnostic functionaility) IIRC was exclusive to Cadillac for a few years, then it appeared in some Buicks and Oldsmobiles, too.

[@michaelcoffey7362]

Cool 😀

[@Polkhero]

It's like an internal Scanmaster!