Testing UVCH (under valve cover harness)Ohming Through 9 pin Pig Tail

[@John-n6g]

First I'd like to thank you on your down to earth method of explaining what you are doing and what we can do!!! I tested my ohms on the idm harness and they all came within the parameters. Only the 5 and 7 showed 3.6 ohms. I haven't yet ohmed out the plug into the valve cover gaskets but will do so tomorrow after watching your informative video. I forgot to mention before that there were times, about a year ago that I would hit the accelerator 2 or 3 times to get a response and it would work and I didn't much think about it since everything seemed to work fine. Could that have been a sign that the idm was heading south or maybe the cps or pcm or the idm, which I'm thinking is the case? I could really use your thoughts on this matter before I start buying parts that I don't need. Thank you for your time in helping me!!!

[@bayoudiesel]

@@John-n6g the accelerator pedal (ie throttle position sensor) is a know part to fail on these trucks. They usually get a dead spot around the usual speed you drive or can sometimes just go out. I swapped one out and a year later had an issue only to find out I failed to plug it all the way in till it locked. And it took a year to have the plug rattle loose. Had to come home from 2 hours out on cruise control cause I had no pedal response. Got real fun timing traffic and lights.

[@TristonDaspit-ls6tx]

Great video!👍👏

[@tonytres7687]

Hey I have a 99 Ford f350 with 7.3 i scanned it weeks ago and it gave me codes on the obd scan , now I wot (wide open throttled it ) now service engine light came on it is running a little rough barely noticeable. When I go to scan it it tells me no obd codes stored and ecu no response. Kinda weird , I washed the motor like 2 weeks before .

[@bayoudiesel]

How do ya get a “no codes” when the ecu isn’t communicating?

[@bayoudiesel]

Usually if u have electrical trouble after washing a motor u need to dry out or spray out ur electrical connections with contact cleaner. I’ve also used Ed-40. Need more info to take it further. Keep in mind that all these girls are over 20yrs old so bad wiring is an issue which would be exacerbated by washing as well

[@recruit_life0715]

man im loosing my butt on this truck. I talked to ya yesterday on another video. this thing ain't throwing codes and passed the buzz test but i got a nasty misfire. I'm ohm the uvch. inj 6 is like 25.0 rest are fine. now on glow plugs only 1 is reading with 0.4 the rest have zero resistance.

[@recruit_life0715]

sorry to bug ya so much I just can't afford to throw parts at it til fixed but I'm not the best diagnostic guy. what does it sound like to you?

[@bayoudiesel]

@@recruit_life0715 not a bother my friend. I totally understand how quickly money can fly out the window with these girls. So ya all cylinders have passed the buzz test but 6 is way out of spec. That seems odd. How does 6 sound compared to the others when buzz tested? Sharp or muffled? As for glow plugs, you may need to replace the set if you don’t know the history and if a large number are failing. It’s kinda hard for me to say not being familiar with the history of the truck. You can physically test the glow plugs while they are out just have to be very careful cause they get really hot really fast. Let me know if u want info on that.

[@bayoudiesel]

It may be more time efficient to kick this around over the phone vs text.

[@recruit_life0715]

@@bayoudiesel it's my boss man's truck so I can have any history on it if I ask him. he's the one who did the buzz test said he did them all. then individually. some sounded different but nothing crazy. which led to me trying different idm and testing harness etc. I sent my number if you wanna give a hollar. I don't wanna tie your whole day up diagnosing over the phone. if you got free time this evening or weekend we can chat about it when boss man is here so you will have a better understanding of what's goin on. really appreciate your time sir.

[@bayoudiesel]

@@recruit_life0715 haven’t seen an email yet. But I should be free some this evening to chat. [e-mail]

[@Big-kon]

I ohmed my injector uvch just like you showed here and all of mine except 2 and 4 read 3.9 ohms. Cylinder 2 read 4.3 ohms and cylinder 4 read 4.1 ohms. My truck is pouring out white smoke that smells like raw diesel. No matter if it’s up to temp or cold. I already replaced the icp and the cps. Buzz tested it and the buzzes were all over the place. Did a cylinder contribution test and cylinders 1,4, and 8 all came up as a problem. What do you think? Any help would be greatly appreciated. The truck is an early 99 f250 powerstroke.

[@bayoudiesel]

So it appears you have some injectors dumping fuel which causes the smoke and rich diesel smell. Assuming there is nothing going on compression wise in a cylinder lets start with the smaller stuff. If I remember correctly injectors ohm good when between 2.8-3.6. All this tells ya is that the electrical side is ok or not. Could be wiring, connectors or solenoids. This can test good but the injector still have internal mechanical issues. On my scanner a buzz test will come up with a pass/fail for each cylinder which can most of the time be confirmed by what you hear as well. Did buzz test indicate any failed? Or do the same suspected cylinders sound different? In my opinion the cylinder contribution test is a good way to spot trouble. At least which cyl. According to your info cyl 4 has failed both ohm & contribution so that may be a big part of the your problem. cyl 8 almost always comes up on contribution due to the AE injector it uses and I don't usually worry about that unless i have another indication that 8 is bad. Because you have cylinders indicating problems on both the left and right banks I would not think trouble with the 9 pin uvch plugs but it is a good habit to check them. So that leaves us with 1,2,4 and maybe 8 causing problems. To narrow down that it is actually the injectors and not wiring you can swap good and bad injectors around and see if the problem moves by re running your previous tests. If location stays the same, meaning 1,2,4 ect then wiring may be the problem. If it follows the bad injectors then you need some injectors. Sorry for the length. Feel free to hit me up on my e-mail [e-mail] sense this is kinda long winded for comments. lol. Hope this helps ya. Let me know what you find out or if you have any other questions. Thanks for giving my channel some of your time. If you get something out of it please share it around.

[@Big-kon]

@@bayoudiesel brother you are the best! You’ve got my sub. I’ll send you an email in the morning. Thank you so much! 🤙🏼

[@bayoudiesel]

@@Big-kon just paying it forward. Hope it helps u get the ole girl feeling better. They can be moody bitches some time. But when they are feeling good there is nothing better.

[@John-n6g]

I think I also forgot to tell you that I have a 1316 code and know that doesn't necessarily mean that changing the idm will fix it. Thank you again!!!

[@John-n6g]

Oh yeah, I pulled the idm and it's got a good amount of corrosion on the box and the black paint is easy to flake off and near the vent there is a bit of bubbling under the black paint

[@bayoudiesel]

@@John-n6g I’m happy to help any way I can. You first comment was about the pcm. Then we moved to the p1316 idm code. It’s always possible that any component can fail but in my experience the 1316 code is usually wiring / connector related. Before we get too far into the weeds can we back up a bit? Tell me what’s been going on with the truck and let’s make sure we are on the right path.

[@themechanicman3865]

This is for the new style what about the old style I've been having a hard time finding the old style read

[@bayoudiesel]

Are you referring to the pin out for the valve cover harness for the obs (95-98) trucks?

[@jamesfaison9410]

1999 F350 7.3 Codes P1316 and P1275 P1275 only appears after performing injector buzz test Any recommendations on approach?

[@bayoudiesel]

The codes from 1271-1278 are trouble with cylinder 1-8 respectively. Yours is 1275 so cylinder 5 ain’t happy. The majority of the time that I see this code it is a wiring / connector issue in the engine harness or uvch. May possibly be the injector itself or the idm but usually wiring. Time for some investigation. You can pin out with an ohm meter, you could also swap sides with the uvch’s and see if the trouble moves.

[@jamesfaison9410]

Tested glow plugs. Test light to battery positive. Test light lit up on every cylinder. Driver side valve cover: cylinder 2 showed 5.6 ohms when tested on the vehicle. Removed valve cover gasket and retested. 0.01 ohms on all cylinders and glow plug circuit. Passenger side injectors within specs at 3.0 - 3.2 ohms Valve cover gaskets are one piece. Unable to use the quarter trick

[@bayoudiesel]

@@jamesfaison9410 I would have to look up spec for glow plug ohms to remember the range but I do know that new OEM plugs usually him out to 0.4. If glow plugs are in spec when tested directly to the plugs but the previous test through the harness tested too high then the harness seems to be the issue. Glow plugs and test light will light up as long as it still has continuity but can be way out on an ohm test. But this test is great for quickly determining if any have blown

[@jamesfaison9410]

@@bayoudiesel I don't suspect any glow plugs issues. We had some severe cold weather last month (Memphis, 0°F) and I had no starting issues without block heater plugged in. Cycled the key a couple of times and engine fired right up. On the driver side valve cover gasket for cylinder 6, I found the wire sheathing was broken all the way around, exposing the wire. I'm going to replace the valve cover gaskets and the external pigtail

[@bayoudiesel]

@@jamesfaison9410 that’s the direction I’d go. Let me know what ya find out. Or feel free to hit me back with a question if ya need. Good luck.