I finally got around to installing my e-fan. I had a little problem where I forgot to put those blue pin covers back on the pcm first. Then bent a pin or two, and one was pushed in a little. I straightened and fixed em, finished install, and the truck started right up. I drove it around the block. Shut it off, and then 30 minutes later I connected my hptuners for the first time. I plugged it in with the key out, and only went to accessory to read, but couldn't connect to pcm. (I was pretty tired at this point, and honestly I might be missing something as I retell it). I tried my code reader and it says it can not connect. My battery is 6 years old, and I thought I had finally stripped out the negative terminal. I thought I was all badass, when I did this

with these on the top posts connecting 1/0 cable.

using these two covers to keep from ever accidentally creating a connection I don't want specifically with that little corner brace bar:


But that was gone quick..... I'm only getting about 10 volts, and not sure what to diagnose. I have removed the pcm, and checked the pins, which all look fine. I don't know if I fried something in the pcm, or if I used hptuners wrong and screwed something up that way or something else. Even with 10 volts it cranks over fantastic for about 1 turn, just as if it has no fuel (even though I know there is a full tank) and then its as if it gets lethargic and quits. Can someone help with how to diagnose this?

 

Tried a passlock relearn thinking disconnecting the PCM with the battery disconnected for a couple days might have done something. 10 min to ON, 10 sec off (x3), then start, with no luck. I think that's not it, because I'm not getting a connection to the PCM.

 

1st off you can not connect to the PCM in accessory mode. Key has to be on in run position but engine off.

Second do not flash or read the PCM with only 10 volts on the battery. You will likely brick it.

Either charge the battery to get the correct 12 volts or replace it.

 

I wasn't sure on that, but I was trying it in the run position.

I did replace the battery. Brand new Redtop, and still only getting about 10 volts. (Showed no difference after new battery). I'm reading how interference from a stereo is something that can cause a bricked ECM. I have a 3 amp setup that I did not pull any fuses out prior to connecting.

 

10 volts where?

 

battery voltage. my mistake, its about 11.75 volts.

I went and just ordered a ECM from someone that will send it with the VIN, mileage, and a HPTune already on it. At worst case, I will pay a little more than pulling a spare, and I will have a back up ECM that I can do something with. Hopefully, I'm not just buying parts, but this seems like the obvious problem to me.

 

I got my replacement ECM in yesterday, and swapped it in. I'm up and running but still having what I'm certain is all one issue. I get: the battery light flashing (even with 12 volts off, and 14.4 volts running), the low fuel light flashes and the tank gauge shows empty, (I know there's nearly a full tank in there), and the security light flashes. They rotate constantly, and do this after the ten minutes on the relearn. I think I'm only running because VATS has been removed. I also get no connection with my code reader, and it does not read coolant temp. Everything else is annoying, but this is my concern and motivator to fix this. I don't usually sit in traffic, but this means I can get coolant to flow, but the fans won't turn on until it reads. All of these problems were happening before I swapped my ECM. I think all swapping my ECM did, that is allowing me to run, is that it removed the VATS, (which can't be fixed until I get a data connection).

Every other thread, people suggest it's a ground, but it never got answered. I originally ground the e-fans to the block. I'm using a factory harness, and when I pulled it, I know the factory ground is right below the middle of the fans. I plan on replacing it there when I can find a bolt the right size.

When I first did the efan mod, I wired it up with the relay and through the clutch fan, and then changed it to pin 42 and 33. I've tried to search, and use my PDF manual to gather information on circuits and connectors, and am convinced it is a "(class 2 serial?) data connection from the BCM". If anyone knows, I read you can't just swap the BCM; you have to have the correct RPO codes to be able to swap that. I don't think its the BCM specifically but just curious.

I read how others were also having problems with trip and cruise and want to check those out later today. I know the BCM is under the DS knee bolster with 3 connectors. I want to make sure those aren't burnt through, and with the little bit of electrical training I have, start isolating circuits, (just need to go through this manual to see what I should be looking for specifically).

 

What year is the truck?

 

2002.

I do have trip and cruise. I also have a steady ABS and airbag dash lights

 

The ABS and Air Bag lights are new?