P0500... again

The digram for the combustion meter doesn’t show it, but the speed control is certainly tied to the Cruise Control / light.

Why it’s flashing? That’s for the other guys in here 6Gear and Dm93.
Those 2 guys know much more about this stuff than me.

 

That's very interesting, so perhaps something in the junction box is shorting out or open?

I don't get an opportunity to work on these trucks much (they just don't show up in the shop much), I do testing and research on my own truck when I have time to try to better help people that are having issues but it's not the same as diagnosing a broken one and service info flow charts suck to follow.

 

I'm not sure, the cruise control and light is entirely controlled by the PCM. All the cluster does is receive the vehicle speed signal from the ABS module (A/T) or the output speed sensor (M/T), reads it for the speedometer, modifies it slightly, and passes it out to the PCM and other modules that monitor vehicle speed.

 

I’ll admit. I didn’t take a look what OP jumped.
I was more focus on the flashing light.
I can live with out CC, but the flashing light not so much.
I’d want it on or off.

But…….That isn’t fixing the problem either.

 

This is the only place I see mentioning a blinking cruise light in service info.
And whats a combustion meter?

 

Hummm, well now to see if it threw a CC Code?
It says it should?

 

A combustion meter shows the current state of my frustration.
When it reads full, those around me should take shelter. As there will soon be a fit rage with objects flying through the air that may cause serious bodily injury.

 

Strange like you said, it’s almost like something is “back feeding”.
Weird how OP’s light flashes faster, slower, or not at all depending on the speed?

 

You mean C9 Pin 19 right?

 

Yeah, 19. Typo due to incessant frustration and tiny digital keys.

 

This is interesting...f'd up, but interesting nonetheless.

It seems you've gone through everything, but have you checked the CC stalk wiring? I read it somewhere here that the stalk is switching different combinations of 2 or 3 resistors to select the desired operation. Turning CC on/off was the 0 ohms output iirc.

The jumper makes everything work but the CC light blinks relative to speed.

This tells me that either the wire that you jumped out is not a straight shot. It's stopping somewhere before it gets to the dash meter.

Or, there's an intermittent short/open somewhere.

I dunno just a thought...

Good luck.

 

The jumper is certainly a straight shot, but the original wiring is also still plugged in. So my multimeter says I have continuity in the harness from the cluster to the ECM, and I have a good signal from the cluster to the ECM as made evident by my jumper experiment, what is happening?
Side note, anyone ever look inside the j/b 2 next to the ECM? Decided to pop it open considering the circumstances. It’s odd to me there are so many breaks in the wiring - some of them have jumpers but some don’t. There’s also jumpers on lines that aren’t even cut? Going off on a tangent here..

 

I have not taken a look at it.
But you are dealing with the lower right hand corner in the picture below.
see how they are all “spliced” together?

 

Work’s kept me away from this project for a while now but I’m looking to jump back into it with a little help from my friends
Any of you guys still lurking out there have any more ideas for me? I kinda ran into a wall and don’t know where to look next. I’m almost ready to take it to a shop but The natural worry is they’ll just start throwing parts at it.

 

Gotta provide an update and close this thread. Appreciate all the help. Eventually I needed to pay someone with an oscilloscope to look at the cluster signal; I couldn’t troubleshoot any further. Turns out the signal sent from the cluster to ECM was erratic. Sometimes it was sending it properly. Perhaps this is what led me to rule out the cluster when I made my jumper wires. In any case, I sent my cluster to Automotive Circuit Solutions in Missouri (they’re also an eBay seller by the name speedy_repair_service). They turned it around in just 2 days, charged me only $150, and my P0500 is gone! As an added bonus, my low fuel light works again. They go through everything on the board and warranty the work for life. Thought you all should know this as replacements cost ~$600. This is the least expensive repair service I’ve seen and they were very professional. Good luck to anyone else out there dealing with this!

 

Thanks for coming back to update