Got Codes 35 36 42 57 62 78 84 & 99 !!!

[ol9465er]

Hello, can anyone help...

I all of a sudden got an Engine Service Light and when checked codes got: Code 35, 36, 42, 57, 62, 78, 84 and 99.

Code 35 and 36 are Pulse width Errors
Code 42 is Fuel Temp Low
Code 57 is PCM 5 Volt Shorted
Code 62 is Turbo Boost Sensor Cct Low
Code 78 is Wastegate Solenoid Fault
Code 84 is APP Cct Fault
Code 99 is APP Cct 5 Volt Reference Fault

The most common denominator, that I can see is the 5 Volt Reference Voltage, except for the 35 and 36, which leads me to think loose connection at PCM, PCM faulty or ground fault, or maybe sensor(s) shorting. This is what I am going to check for.

The Codes 35 and 36 I am not sure about in this case. I had these of course with my failing stock PMD, but since I installed a SOL-D FSD and have not had these codes since.

Has anyone had a similar case and did the 35 and 36 set also.

Any comments or help appreciated.

ol9465er
1994 Chev 3/4T 6.5TD 4X4 Ext Cab
Stock and original except for SOL-D
286000 Km's (178,750 Miles)

[Barry Nave]

The SOL-D took care of my code 35 also.
Are these codes still coming back after clearing?
I'd deal with the 62 78. One code will just set others.

[Iain]

If your pump goes then you will get a lot of odd ball codes. When my pump started acting up, I chased codes after code and scratched my head a lot before I finally took it to a repair shop and they told me it was the pump (replaced under warrenty). If you change the pump out, make sure you put a FSD Cooler on your truck to alleiviate the overheating of the PMD.

[moondoggie]

Good Day!

DTC 35 - Help! (http://forum.thedieselpage.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=1;t=004386#000000) (Click in colored text) might be worth a look, I don't know. I know over the years I've heard of lots of folks experiencing grounding & other electrical gremlins as these trucks age - worst crap to try to find, IMHO. :mad:

Blessings!

Brian Johnson, # 5044

[More Power]

In general, whenever a variety of unrelated codes appear, it is due to either an electrical problem or a PCM problem.

Check all battery cable connections, check all ground connections, check alternator connections, check electrical connectors, etc, and lastly don't rule out a defective alternator.

MP

[Kennedy]

Originally posted by More Power:
In general, whenever a variety of unrelated codes appear, it is due to either an electrical problem or a PCM problem.

Check all battery cable connections, check all ground connections, check alternator connections, check electrical connectors, etc, and lastly don't rule out a defective alternator.

MP Agreed Also check ignition switch.

The 78 and 62 diagnostics would benefit from having a boost gauge to see what the boost is doing.

[JohnC]

One thing to look for is a short in the wiring to one of the sensors. The "5 volt shorted" code indicates thepower to the sensors was shorted out. All the other codes could be caised by loss of power to the sensors.

'Course it could be a fault in the 5 volt supply in the PCM...

[ol9465er]

Thanks to all for the suggestions. Today is testing day!

I have noted one more thing though - I think it is heat related. I live in Vancouver, Canada the weather has been warm here 25*C (77*F) in the afternoons but cool in the morning. When my engine temp guage reaches 85*C (185*F) that is when the SES light started coming on. In the cool morning it was fine.

Once it has come on, I notice that if I am asking for power or cruising the light stays on (heat up), but if I can let it coast for a bit and the temp guage goes down slightly the SES goes out. As soon as I give power again the SES light comes on.

Codes 35 and 36 I am still unsure about, the may just be the result of voltage fluctuation (a symptom?).

The others I am starting to reason this way:

Code 42: 5 Vdc is sent through Cct 1578 to the fuel temp sensor - maybe the temp sensor is shorting taking the 5vdc down, or maybe the fuel temperature is actually high (creating low 5Vdc). I am changing my fuel filter today in case this is restrict fuel flow and less cooling of the fuel, however I don't seem to have power problems (but you never know).

Code 57: Cct 416 feeds 5 Vdc to the EGR and Baro Sensor, it also feeds the Crank Position Sensor and the Boost Sensor. It could one of these be breaking down with temp dragging the 5Vdc down again.

Code 62: Again Cct 416 - Could be Crank Position (CPS), Turbo Boost Sensor (TBS) or Baro Sensor (BS) shorting with temp.

Code 78: I think this is a result of low Reference 5Vdc (a symptom). Again, Cct 416 and connected to CPS, TBS, BS and EGR reference voltage.

Codes 84 & 99: Again, I think this is a symptom.

Has anyone had experience with heat related issues with any of these, EGR, TBS, CPS or Fuel Temp Sensor and which may be the most likely culprit.

Any suggestions for tests for these sensors? I do not have a Scan Tool.

I am also going to check for connections that may be faulty because of heat (especially Cct 416) and disconnect and reconnect all PCM connector and the sensenor connectors.

Thanks,

ol9465er
1994 Chev 3/4T 6.5TD 4X4 LWB
Stock except for SOL-D