Random Codes, Lost Communication

[Ian Mills]

My truck has been acting a little funny lately. I haven't been left high and dry yet but you never know when it will get worse all of a sudden.

Symptom 1: If the RPMs drop suddenly after the engine being under load for a while, the computer throws P0332. This usually happens when canceling cruise control on the highway. I took a road trip last weekend and it happened 4 times in 3 days. Every time was cancelling cruise. I would reset it with my scanner at the next stop each time. It doesn't happen every time cruise is cancelled but enough to be noticeable. (The knock sensors and their wiring harness were replaced recently with good Delphi units)

Symptom 2: Twice in the last month or so I'll be driving along and the dash lights up like a Christmas tree. Every light. The first time it happened at the same time as the P0332 with cancelling cruise, the second time it was all on its own. It threw maybe a dozen codes each time. Some of them were U1041, U1026, P0446, P0327, P0060, P0059, P0054, and P0053. I don't have all of them written down but that's the general idea.

My first thought was a ground and I've checked a few but the problem was not affected. Are there grounds I should definitely re-check? Does anyone know which grounds these sensors and modules are connected to?

Alternatively, is this a bad ECM/PCM?

[Ian Mills]

New symptoms:

-Fuel gauge will go to empty and the low fuel light will come on. Stays that way for several minutes and the comes back. No codes. (Fuel pump assembly replaced in January with new Delphi, gauge cluster is new in September 2020)

-Battery warning light comes on but voltage gauge acts normal. Truck runs normal. Light stayed on until ignition cycled. No codes.

-Service 4wd notification comes on in DIC and stays on until ignition cycled. No codes.

-Airbag light comes on solid. Stays on for a few minutes, goes back off. U1088

-Gear indicator light and transmission respond several seconds after moving the physical gear shift lever. Only a few times. U1026.

It seems like a computer issue to me. What do you guys think/which computer?

[diyer2]

IMO

Electrical issues require an elimination process. 

Instead of guessing start with grounds. Find them all and redo them to make sure they are not the problem. 

Is the battery good?

[Ian Mills]

I did check some of the grounds. As mentioned above I was also interested in which grounds are relevant to these issues. If you have a comprehensive list of grounds for a 205 Silverado 1500 CCSB, that would be helpful too

[Ian Mills]

I got a freeze frame of the P0332 code from my scanner (innova 5410) The pictures didn't turn out well so I'm just going to type out the results. This occurred after driving on cruise (set to 68) for approximately 10 minutes and then cancelling by tapping the brakes lightly and coasting. Do any of these look off?

Fuel Sys 1 - CL

Fuel Sys 2 - CL

Calc Load - 13.7%

ECT - 203 F

STFT - B1 0.0%

LTFT - B1 0.8%

STFT - B2 0.8%

LTFT - B2 3.1%

MAP - 6 inHg

Eng RPM - 1603

Veh Speed - 63 mph

Spark Adv - 27.0

IAT - 70 F

MAF - 1.21 lb/min

TPS - 14.5%
 

The other issues are still happening intermittently. This is by far the most common symptom, I cant figure out why it's happening. I rechecked the connection where the Knock Sensor harness plugs in the main harness, I rechecked the main harness ground to the firewall.

 

Edit: The truck also threw a P0327 which (along with the other above symptoms) leads me to believe that it's not just a faulty replacement knock sensor

Edited June 25, 2021 by Ian Mills