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What Did I Do? DTC 34, 35, 36, 39

JohnShead

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Kingsport, TN
DTC 34: Injector Pump Stepper Motor
DTC 35: Injector Pulse Width Short
DTC 36: Injector Pulse Width Long
DTC 39: TCC Stuck Off

My truck was running great, no codes at all but I couldn't keep my wrenches off the old beast. I had a (25 year old) hydraulic hose burst and decided I would change all of the hoses along with the pump and oil cooler. To resolve some electrical issues years ago I had installed an 8AWG THHN wire (not automotive but that's what I had in a box), I bolted it to the firewall, then to the grounding stud on cylinder no 8's intake, then to the stud where the right side battery is grounded, then to the stud where the left side battery is grounded, then to the frame by the PS pump. I recently resolved those electrical gremlins so I decided to remove that ground wire. The problem was all in the plugs that attach to the side of the main ignition switch plug, they had some connectors that were intermittent and some were just poor connections. I also had been procrastinating on a repair that I decided to do this time since the truck would be inop for a while, I had a minuscule coolant leak coming from under the timing gear cover. It was such a small leak that I tolerated it for years, sometimes it wouldn't leak at all and other times it would leave a silver dollar size puddle on the garage floor overnight. I finally decided to fix this and for the umpteen thousandth time I tore down the front and top of the motor to get at that leak. I chiseled a nice new mark on the IP so it would be back in the same position when I put it back together. I took the nuts and the gear off of the IP to pull the cover, cleaned it all up, applied new RTV, and reassembled it all without cranking the motor at all. When I got it back together she fires right up and seems to run fine but I get the above codes. With those, of course, I have no TCC lockup or cruise control and I'm pretty sure it's not going into 4th gear. Does anyone know if I might have knocked something loose to cause these codes, or do I need those grounds maybe?
 

MrMarty51

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OK, I do have some. I'll try that. Probably be tomorrow though.
That will be a 1/4" ID hose.
Recheck the grounds at the back of the right side cylinder head. Be sure that they are shiny clean and tight. I dont remember if there are three or four wires back there.
 

JohnShead

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Kingsport, TN
Update: Thanks for the input y'all. I removed my elaborate ground wire as described in my OP because I knew it was overkill after I tracked down the real electrical problem I was having at the steering column plug for the ignition switch. The air in the lines made the most sense as I had removed both the fuel line and return line to the IP, and after pondering the problem for a while I realized that the check engine light came on but went off again a couple of times during my test drive. After returning home and attaching my scanner there were no current codes, I only got those codes when I pulled up historic codes. I cleared them and drove the beast again with the scanner connected. I accelerated up to 80 on the freeway ramp with WOT without the IP codes appearing again, it felt really good too. I do still get DTC39 so no TCC lockup but now I can drive it. Troubleshooting checklist for code 39 starts with the BPP switch which according to my Tech2 is working. All of the relays in the transmission were replaced recently so I don't think it's that but IDK yet.
 

Rockabillyrat

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Code 39 is set when the PCM is commanding TCC lockup and it sees more than 65rpm in coverter slip speed. ECT, APP, and BPP will effect lock up strategy but they wont set a code.

Clear it and test drive it while monitoring slip speed and TCC lock up %. If slip speed is over 65rpm and TCC % is in the 90s then the TCC is either mechanically bad or you have a issue with the solenoid and/or wiring. You can test the solenoid and wiring easily but doing a amperage flow test.

I replace ALOT of GM transmissions for a failed TCC that contaminates the rest of the unit with friction material. Sometime I catch it early enough and can get away with just the converter.
 

JohnShead

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Thanks Rockabillyrat for the detail on code 39. I appear to have a faulty ECT sensor as my Tech2 shows 53°F but I just took it on a 20 minute test drive and it's way warmer than that. I haven't changed it yet but that would explain the code and no lock up. I drove it before reading your post so I wasn't monitoring TCC% or slip speed, I'll do that after I track down the ECT problem if I need to.
 
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