My truck has quite some miles on it so it does tend to be a bit hard to start when it is cold. That being said, it's never been like this...
First, the things I have done in the past year or less while working on other maintenance items to help rule out what the problem isn't:
- replaced GPs and GPR as well as checked that GPR is actually providing voltage
- replaced the IDM (now carry an extra spare in the truck)
- replaced injectors (went to stg1 single shot) and fuel pump
Now for the problem. When it is cold, and only when it is cold (40F), the truck will not start. Regardless of whether it is plugged in or not. The truck turns over and batteries are fully charged, it just won't catch. The problem is somewhat intermittent, but worse the colder it is. Below 40F it is almost impossible to start. While trying to start and motor turning over, I can hear a relay clicking repeatedly behind the dash (where the radio is) - I think this is where the 5 light relays are. When I hear the relay clicking, I know for sure the truck isn't going to start. I can wait some time and try again and when the relay clicking doesn't happen, the truck always catches.
It happened to me again this morning and I had my laptop and AE handy, so I quickly ran the KOEO test and came back with two codes:
P0605 - Internal Control Module Read Only Memory (ROM) Error
P1668 - PCM/IDM Communications Error
I think I've had the P0605 error before since I got a chip, but I definitely haven't seen the P1668 error and it doesn't show when the truck starts.
Here's a youtube video of what it sounds like when it won't catch:
Do I have a bad IDM yet again or should I be looking at the ECU?