Hi Robert- could be bad grounds - I had a situation where my speedo would drop to zero everything else was fine, ECU was still working. After a week on this I found if I turned enough power on I could make happen - the heater blower motor was ideal.

Turned out to be 1 single loose ground in the engine compartment, I have been slowly hunting all the grounds down and checking them.

As far as I can determine these trucks react weird to ground faults.


I believe your odometer info is stored on the ECU - no ECU no Odometer

 

Man I'm really torn about this, but I feel like I keep getting conflicting info. This morning it started up fine (I wanted to make sure it warmed up ok). I went back out to go for a drive 30 minutes later and it wouldn't crank.

I put in the iCarsoft to watch the live data as it cranked and it wasn't reading any RPM while cranking (should it?). I think I'm going to eat it and buy a new Bosch CkPS next week. I may even spring for genuine. It's kind of starting to bug me that its not reliable right now.

 

It's my understanding that's the only way to check for a bad CPS since it throws no codes.
Sounds like yours may be bad?

 

This would be the 2nd bad CkPS to my knowledge in this vehicle. Once by the previous owner, once by myself about 1k ago and now there is a good chance its happening again.

What's the best to get? Bosch? OE?

 

This is the one I bought here.
I find an online coupon and pay for it with paypal on their website and pick it up at the store.
I think I got it for under $40 bucks a couple years ago?

 

I replaced the CkPS today and so far it looks like a fix. I'd have to thank wjsj69 for pointing out that not all CkPS die a clean death. That and a lack of RPM reading when I was having problems cranking lead me down this path.

I'll be keeping a close eye out for this issue. I ended up getting an off-brand from Oreilly's since it was in stock and had a lifetime warranty.

I'm going to knock and wood and call this resolved.