Monte Carlo SS 1986 gauge cluster, speedometer removal and tachometer repair

This is a follow up to highlight the tachometer repair but also as a follow up to my led bulb replacement to inform on overall bezel, speedometer and tachometer removal.

[@invaderzim133]

Just fixed my tach with the help of this video! Thanks!

[@jsljjlsl1027]

Good vid about to reassemble mine after being off for about 6+ months

[@bigglefty75]

very helpful video thank you sir!

[@shovelheadpec]

Great video young man I have 88 so monte msd ign. Stock tach works at idle but going down the road it runnin redline ? I know it's stupid simple Exact cluster as your 86

[@frankprior204]

Great video but I have a question. I see you cut pin 10 & 4 and soldered in a 200 ohm resistor but when you show the final product I see a second resistor also soldered in is it necessary to have 2 resistors?

[@mondottimondotti7318]

1st Apologize, but I don’t see what you are seeing. The only thing that I could see that maybe you thought was an addition is the resistor on the opposite side that was already there when I started this project. If so, that was the way it was when I took it apart. Secondly, I reviewed my post and see that I did call it a 2K resistor at one point in time although all other, including when, pointing to it on the schematic, I correctly called it the right value which is 200 K. So I do apologize for confusing you, but it is a 200 K resistor, and only one resistor that I am cutting out of the circuit by cutting the pins on the I C, and then replacing by soldering a new 200k resistor across those points on the PCB.

[@johnnyjohn8073]

My 79 El Camino came with the dummy light clusters & the clock, instead of the tachometer. If I replace it with the electrical gauges system, including the printed circuit, will the tachometer work? Or does the main cable that connects to the printed circuit would have to have the wire that may be missing since it originally came for a clock cluster? In other words, will the wire on the plug be missing since there was no tach? I don't want to install an exterior after market tach.

[@punch_bowl_turd3005]

hey, your 86 has a 115 spedo too...? i have/ had too and the 1st 1 i totaled had a 85mph do you know anything bout this?

[@CRXSLY]

did you have to add something to the LS output signal tach to fit the oem carlo input tach?

[@mondottimondotti7318]

Short answer is yes. Long answer is it depends on your LS ECM. When I did this video I had what is known as a 24x crankshaft reluctor wheel and gen III ECM. Since our cars have a v-8 Tach I programmed the ECM resolution to match with tuning software is 3/3 for 24x with pull-up circuit (do search on HP tuners Tach resolution ). Now I have a 58x or gen IV ECM and resolution is 7/7. But will share later in a different post issues I encountered as I am currently working on this.

[@iamlazarow3526]

On the 3 pins behind the tach, do you know which is pos, neg, and signal? I have this same tach and i want to hard wire it. Thanks.

[@deankay4434]

Using a digital multi meter (DMM). Place loose electrical connectors secured off to the side, then connect the battery. With the key on, place the black or negative meter led on the chassis ground, like the steering column brackets, then test each of the 3 terminals. B+ for one, ground for another and the “Tach” signal should fluctuate with the engines speed. A DMM is 10 mega-ohm internal resistance so it will not add impedance to the circuit causing issues effecting the reading...or the circuit. Start with your meter set to read DC, take note of the reading and position. Switch to ohms while running to find ground. Once those two have been identified, switch to dc voltage and if it is jumpy with engine speed, it is the “TACH” signal. This model year uses “HEI” ignition. It has three wires on one end. Ground, B+ with key and tach signal. Depending on who made the distributor cap, it maybe cast on top. The larger wires are power & ground, while the tach wire is smaller because it doesn’t carry hardly any current / amperage. it has to be there and plugged in. Over time, the tach wire could be left unhooked. It runs from the dist. to the gauge only. Many wires can be moved, relocated or re-purposed. But the should be three wires at the cap. Tighten the female clips with needle nose and I would use dielectric grease on the terminals. Notice, he said 2K ohms. That is 2,000 ohms, not two hundred. Hope this helps anyone who reads this becuase the cost of a replacement tachometers is like buying 2 sets of truck tires, mounted, balanced and extra for road hazard. Retired - ASE Master Tech since 1978

[@mondottimondotti7318]

I recently replaced the stock one with an 8K Tach from Mike’s Montes. While doing so I noted the labeling on the back of the terminal posts. The single post by itself is the coil or Tach signal input. The two posts on the opposite side are as follows: Ground is on the outside and 12v is the post next to it on the inner side. I hope this helps.

[@suewatson1912]

@@deankay4434 I think they are stated on the tach pos neg and dist.

[@deankay4434]

@@suewatson1912 The gauges including tach for “G” body 1986, plug into the clips in the IP body. The tach is not mark and flexible printed circuit is not marked. The terminals are arranged so if the faceplate locates it’s position. Circuit board has part number and tach in light blue plastic shell. I one OEM entire cluster on bench being cleaned, lubricated with fluorinated grease in small squeeze tube. As shown in the GM shop manual. When using new circuit board I always scuff contacts even when in plastic. Photo can be provided. I am trying to finish my PCV system with Stainless Steel inside 1” copper pipe in valley plate of “LS” engine to drawn crankcase gasses out, putting fresh air in through rocker arm covers. DK.

[@paparice6369]

I can’t figure out how to fix the dash lights on mine

[@FASTFATBOY]

OUSTANDING video. What is the correct name of the "light blocker" shown at 17:45 in the video? I need one. I will use this vid to fix the tach, thanks.

[@mondottimondotti7318]

Thanks.. I Do not know the name but know the function. As you already indicated It prevents bleeding of light into other indicator/lens segments of the front panel. Check with Mike’s Montes if he doesn’t have it no one will other than a junkyard. You could easily make one out of some thin sheet plastic or even cardboard and thin single sided adhesive foam to form a tight light seal on the substrate you decide to use.

[@suewatson1912]

@@mondottimondotti7318 I think they call it a light defuser

[@ericcollins2349]

Do you know a good place to buy 1 for an 88 monte SS

[@sporty4981]

Can u help me fix mine please 🙏

[@mikebilecki]

Mine read 124.6 should I assume it is the same issue?

[@mondottimondotti7318]

Even though it’s less resistance than the expected 200 K it’s still significantly lower than what it should be and as such would give you an inaccurate reading. Just make sure you’re measuring it with the pins Cut as to isolate it as if are measuring it still soldered in the circuit it will not give you an accurate reading.

[@mikebilecki]

Thanks… did the repair and will see when I get it put back together. Doing a few other things so it may be a while. Great video very helpful.

[@joedavidson1437]

Why don’t any of you guys show how to remove the speedometer/ pedometer reset stick knob ?!? I’m down to getting that off & cant 😞

[@mondottimondotti7318]

Knob is two pieces. The outer will slide off once you remove the small flat blade threaded screw cap in the center.

[@googlemall3323]

It's so irritating when people skip key pieces of information like routing the side mirror cable through??? Not one of these guys on KZbin clearly shows how to do that

[@mondottimondotti7318]

Not sure what your issue is as it’s extremely straight forward.