Another turbo boost problem and code p0236

[MrMarty51]

You are having some luck, send some my way. Today in the city 60 Km from home, the GMC truck did it's first gear only tantrum, and had to drive home in first gear. It has not had the problem for 8 months, after replacing the ignition switch. Now it only has 2-3 shift solenoid code, instead of other times also 3-4 and lockup failures, all false codes. There is a bad connection somewhere, will have to experiment with jumper leads.

During trying to figure out the problem with the boost system, I have a small dental file, pulled all the connectors apart and cleaned the female ends with the dental file, used an old points file to clean the male ends.
Might be some corroded connections causing your trans to act up.
I also used multiple jumper wires hooked to various components with back probing, using stick pins. I had the two multimeters setting in the cab and would pull over and switch wires, during the trouble shooting process. That removed doubts about if voltages from and into sensors was correct.

[MrMarty51]

Here is a pic of the dental files. They can be obtained online or possibly a dentist office may have them.
I used the blue one, notice the very thin end has been clipped. I did not want to risk it breaking off inside of a terminal.
I shopped all over and could not find any other tool suitable for getting inside of the female terminals.
IMG_3417.jpg

[grancito]

Thanks for that info. I tried moving the ECM plugs in and out on the road back, but that did not work as it did a year back. The 95 has quick ECM access, not the 94, but the 94 ECM is still sitting on the seat, so will plug it in for a test. A year back I pierced the wires at the transmission to test the solenoids and they were OK. One thing made easy, the code is posted as soon as the engine starts, so no need to drive to test any repair. Also it is OBD1 so I carry a plug jumper wire and can check codes from the SES light, strange that it does not come on when the code is posted.

[MrMarty51]

Thanks for that info. I tried moving the ECM plugs in and out on the road back, but that did not work as it did a year back. The 95 has quick ECM access, not the 94, but the 94 ECM is still sitting on the seat, so will plug it in for a test. A year back I pierced the wires at the transmission to test the solenoids and they were OK. One thing made easy, the code is posted as soon as the engine starts, so no need to drive to test any repair. Also it is OBD1 so I carry a plug jumper wire and can check codes from the SES light, strange that it does not come on when the code is posted.

SES light does not come on when the code is set ?
That could be a problem with the ECM.

[grancito]

SES light does not come on when the code is set ?
That could be a problem with the ECM.

I should have used a body ground to transmission jumper lead first, to test grounding, but was feeling lazy, so just changed the ECM. That fixed it for now, so put the right PROM in it, to suit the diff ratio. I remember doing this a long time ago, and think that the problem came back.

[MrMarty51]

It`ll be interesting, keep us posted.

[quvia1]

I am a little confused with this setup. Did you go back to your vacumme waste gate operation or are you using your mechanical home made turbo master. I am hoping to increase my boost with a turbo master like yours and also lower my exhaust temp. Not sure what my boost is now and the truck likes to overheat on long uphill grades. If my exhaust temps are lower I am hoping temp will also drop. This may sound goofy but I wont know until I hookup a boost gauge.I've enjoyed listening to you guys on this subject as it is very interesting and may apply in my case. Some of my over heating has to do with the truck weighs 12000 lbs. The duromax fan and 80 deg thermostates help but still looking for more power and better fuel ecom (12mpg).

[MrMarty51]

I am a little confused with this setup. Did you go back to your vacumme waste gate operation or are you using your mechanical home made turbo master. I am hoping to increase my boost with a turbo master like yours and also lower my exhaust temp. Not sure what my boost is now and the truck likes to overheat on long uphill grades. If my exhaust temps are lower I am hoping temp will also drop. This may sound goofy but I wont know until I hookup a boost gauge.I've enjoyed listening to you guys on this subject as it is very interesting and may apply in my case. Some of my over heating has to do with the truck weighs 12000 lbs. The duromax fan and 80 deg thermostates help but still looking for more power and better fuel ecom (12mpg).

Yes, the boost system is now back to the way the truck came from GM. I had many issues with the boost system, corroded connectors, bad boost solenoid then about 1/2 way through the diagnostic procedures the vacuum pump failed, then the new NAPA boost control solenoid failed, the the original Delco solenoid failed, ordered a new Delco solenoid and in the mean time took the NAPA solenoid back and exchanged it for another one that failed, three of those. I am now running the BWD solenoid and have the Delco unit for a backup. the BWD unit seems to be performing as it should.

[quvia1]

Thanks. I will keep mine stock and stay away from the turbo master. I will hook up a boost gauge in spring and go from there.

[MrMarty51]

Thanks. I will keep mine stock and stay away from the turbo master. I will hook up a boost gauge in spring and go from there.

Thats a good plan. I like to keep My units as close to stock as possible.
The ECM controlled boost systems works better than a TM, no codes is set when the ECM does`nt see the proper boost and 11 pounds of boost is plenty on these engines.