I finally got this thing running and I went out this morning and noticed that my oil pressure gauge is all the way to the left and does not move. The speedometer will move up and down when I give it fuel. Then the service engine light will come on after it runs for about 15 min. I turn it off and the service engine light stays off for about 15 min then comes on again. anyone have any suggestions. ops is new.

2x on the grounds

With an oil pressure gauge all the way left (0), I would put a mechanical gauge on to make sure you have some oil pressure first. With all the crap you've been thru with your truck I'd hate to see it cooked now! Then go thru grounds again includin' the dash ground. I believe its attached near the ALDL connector. So how did you get it goin'? Very curious to know!

Definitely test it with a mechanical guage. Just because the OPS is new doesn't mean it works properly. And from what I understand, the OPS has two functions. One, to operate the lift pump circuit, and two, to signal to the dash what the oil pressure is. One of these may work while the other doesn't. Checking grounds obviously won't hurt, and could very well solve your problems, but I would look into trying another OPS before going to more expensive fixes.

well butch,. you're back,.. you say you finally got it running,. how?? i think you hold the record for most posts about not being able to get it to go,. with all kinds of fixes and repairs and suggestions known to man,.,. but none seemed to work,. very interesting? reading,.. now you're posting some more really interesting problems,. that might be bad ground related ,..
nickI posted the problem
The mechanic told me that the catalytic conveter was plugged up and full of water. I guess when it blew the head gaskets. I seems to run fine and even has more power.

With an oil pressure gauge all the way left (0), I would put a mechanical gauge on to make sure you have some oil pressure first. With all the crap you've been thru with your truck I'd hate to see it cooked now! Then go thru grounds again includin' the dash ground. I believe its attached near the ALDL connector. So how did you get it goin'? Very curious to know!

Sorry guys the gauge is all the way to the right. not the left

I think I will put a mechanical guage on it and make sure it is getting oil pressure. I put out a post or thread that is titles it is now running on 02/28/08 Basically the shop I took it to couldnt figure it out either, he was basically just checking things and had the exhoust pipe from the turbo off. He got side track and tried to start it with this not connected. it started right up. So we replaced it. it was full of water and other stuff he said. It is running fine for now.

Sounds like connections, Butch - pull the bezel and remove the inst cluster from the dash - check the printed circuit fingers for oxidation\corrosion or burned - if ok, reconnect all and it should commence to function - also, need to determine what DTC is setting off the CEL - I would suggest getting the GMTDScan pcware OBD1 scantool from Stefan Engh - it does everything the Tech2 does for about 1/50th the price - after verifying it 100% against a new Tech2, it's so user-friendly I always use it instead - Engh Motors is a listed vendor, here, so check it out

Once more, for the record, guys - noone here was smart enuff to suggest removing the soot trap as a solution, so continual recriminations are unnecessary, and uncalled for - word up, eh...........

Sounds like connections, Butch - pull the bezel and remove the inst cluster from the dash - check the printed circuit fingers for oxidation\corrosion or burned - if ok, reconnect all and it should commence to function - also, need to determine what DTC is setting off the CEL - I would suggest getting the GMTDScan pcware OBD1 scantool from Stefan Engh - it does everything the Tech2 does for about 1/50th the price - after verifying it 100% against a new Tech2, it's so user-friendly I always use it instead - Engh Motors is a listed vendor, here, so check it out

Once more, for the record, guys - noone here was smart enuff to suggest removing the soot trap as a solution, so continual recriminations are unnecessary, and uncalled for - word up, eh...........


Thank you I thought about pulling the cluster and checking for this since it has been sitting for over a year now. I will check out the scan tool as well. I will let you know if this works or not. I am thinking about putting a mechanical oil pressure gauge on this truck. is the best place to come off of at the OPS and just plum it in there? I saw a post on coming off the turbo oil line, but that did not make much sense to me.

That would be the easiest location, tho - you never want to 'T' anything heavy as the OPS due to the intense Diesel vibration - you should prolly 'T' the turbo supply tube at the front of the block, where there is much less heat - avg turbo temps are 650degF - anyway, an oil pressure guage is really not needed, butcept for local testing - getcher inst cluster working, and you'll never think about it, again, would be my advice

Regarding your speedo - mine does the same thing. Rev it a little and the speedo bounces up to about 10 mph. Every 6.5 I've seen does that.

Have no idea why.

Frequency cross-talk, sorta like when you hear someone else talking way in the background on the phone - speedo is evesdropping on tachometer data

I must have missed the post about gettin' it runnin' again. Thats good the hear Butch.

Regarding your speedo - mine does the same thing. Rev it a little and the speedo bounces up to about 10 mph. Every 6.5 I've seen does that.

Have no idea why.

Thanks ODLAW and gmctd. I have never noticed it before. Maybe I am just a little periniod after all the issues I have had with this truck and how important and touchy those ground wires are. The last thing I want to do is fry this motor or somethng else if you know what I mean. any way thanks again.

I have cleaned all the grounds still having the same issue with the oil pressure gauge. I even unplugged it to see if it would go back down or not. I did not. The truck started with the ops unplugged. I did not think it would start until there was 40LBS of oil pressure. The lift pump did not work either until I plugged the OPS in again.

Is it possible that when I replaced the OPS that I was given one for the idiot light in the dash instead of the OPS for the guage?

Hey Butch, read thru my old OPS thread

http://dieselplace.com/forum/showthread.php?t=179119

Basically you should use an AC Delco OPS. What brand of OPS was yours?

The wire\connection to the guage is open - that's why there is no change when OPS is disconnected - did you do the inst cluster?


OBD1 l\p primes in START, runs in RUN - engine will run without l\p if all up to snuff

The wire\connection to the guage is open - that's why there is no change when OPS is disconnected - did you do the inst cluster?


OBD1 l\p primes in START, runs in RUN - engine will run without l\p if all up to snuff

Yes I did. I used a vey small wire brush then some electrical spray cleaner then let dry for about 2 hours then reassembled.

Use a DOM, check for continuity in the guage wire - or, just ground it at the OPS, that should send the needle zero-ward

I went and bought the AC/Delco switch that was suggested earlier and it is working fine now. The PS245 and OP24471 both cross to the AC/Delco D1808A but just do not seem to work. The OP24471 says it works both with the light or the gauge, this did not make sense to me. Thanks teroma25 my problem was a liittle different than yours but it made me start thinking about things. Now I have a code 15 that is showing up so I will look this up and see what else is going on Thanks all I will keep you posted.