Hi, I am working to resurrect my 93 C1500 Suburban 5.7L K L05 with 16168625 pcm and BDJZ code.
The truck is my "go to home depot" truck and sits out side. Dang pack racks have been in it and it's slowly degraded in drivability and is sometimes erratic. Still, however, surprisingly reliable! I'd like to get it running better.
I'm sure there are many sensors, wires fraying, etc. - so I bought the Moates cable and have TunerRT Pro running. ( I found .adx, .xdf, & .bin files needed on this site - great resource! thanks!. ) The idea is I can find specific problems vs just replacing every sensor and wire.
The only code ever surfaced is a EGR DTC - and it's intermittent. The other two overt problems are: 1) sometimes the speedo will move up to about 20mph in park if I rev the engine. 2) The charge voltage seems too high - sometimes around 16-18 V.
Looking at output from TunerRT Pro - first thing I see is a Injector 2 Fault Detected (constant), Quad Module Driver 2 Fault Detected (constant), and Quad Module Driver 1 Fault Detected (intermittent).
I read on a thread here somewhere that (summarizing) - unless the Tech 1 surfaced the error you can't be sure the error is real as GM didn't necessarily make sure the code for that error was correct. I was wondering if anyone has experience on this PCM and these errors?
I have the Helm shop manuals for the vehicle. It does not list a QDM DTC code (I see that some cars in this timeframe had a DTC 26 for qdm faults, apparently mine does not) nor does it list the quad modules as something the Tech1 would check or monitor.
Regardless, I want to check the wires/relays which the quad modules drive - seems likely problem areas. I can find info on other PCMs showing what pins and relays the qdm's drive. I can't find anything for my specific PCM. If it exists that would be very helpful! Short of that, I've found the pinouts in my PCM for the same components in cars around same time and can assume. Or, I guess, open up the box but I'd prefer not to mess with that unless needed.
With respect to the Injector 2 fault. I pulled air cleaner and just did simple look/see. Both injectors appear to have nice spray fan when I rev the engine. I can't see anything from either @ idle. So it doesn't seem there's an obvious problem. Suggestions on what to do here?
With respect to speedo weirdness - looking at circuit the speedo output comes directly from the VSS. I can't see how a pulse train from the engine (is RPM from the crankposition sensor or distributor?) could get to the VSS. I'm thinking either it's a bad ground or the high charge voltage is messing up a reference in the VSS. or the VSS is bad.
I'd appreciate any insight, experience, good or bad suggestions from group.
Thanks
Ed
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