Wonder why it fired up the first two times then nothing??? I've never seen this either, but sure am glad you figured it out!

 

It's been a while since I used the wrong key in the f150 but I think it did fire up then die as soon as the truck realized the key was wrong. It would maybe run 1 or 2 seconds. I wonder if it locks you out after a couple of tries? I bet that's you problem though

 

Well, i thought we were out of the water, jigged too early. I pulled the chip again to see if it would start without. Nope... so i put it back in fully expecting that was the issue, taped everything up nice and tight as the PO carved out an opening in the plastic cover shield to the pcm, and left it somewhat exposed on the chip. Reinstalled the chip, put the dash lower back together... had a beer thinking we were in the clear...go to start it before I walk out, and once again nothing. Now with the chip in I am not seeing 3000 plus from the icp, i see about .85 volts, and 500+ psi, still no start. this is pretty odd...

Wonderful, now I pull the codes and get one for the GPCM, CPS, and EBP... non of which were there before, and the previous expected 3 are gone...

Replaced the CPS with a new OE unit.... still the same code.

The weird thing is the darn ucranks over like it has 2 sets of batteries. Weird part is AE says the bat voltage is around 10.1. At the batteries its 12.5 with the key off. I put two chargers on the batteries and am taking a break...

I'm going to head out in an hour and try before bed. its 11 now..

On a side note I'm pretty angry as the chip was not burned with what we requested...Or so I believe. I called them via phone prior to ordering, ordered on their site and put a small paragraph in the notes section regarding all the mods/injector size and so on, and in addition filled out their burn request form. 3 different inputs. The chip came in a small bag, and the business card had the canned tunes from the site on the back. I sure as chit hope that is not what is on there... Until I can get it running as it should I will not know.

Agreed. see above as what has changed has me quite confused...again!

 

Just to follow up. I went back out and it still did not fire with 11.8 volts while cranking.

P0380,P0340,P0470, AND P0500.... All of them correlate to an open ground circuit, or PCM failure. I'd like to find the pin number for this...

I'm hoping this is a circuit issue I would have a very hard time believing that installing the chip fried the pcm.... unless this was not the right chip for this truck.

I'm so over this crap.

 

What year is the truck?

 

Well I know I am talking to myself now but take a look above and see the blue line mid page called VREF. reference voltage... this is my problem. As every sensor that is throwing a code is linked to that circuit, the ICP is too but its not throwing any sort of code... that may mean something.

If anywhere in the harness that wire is chaffed thats our problem I believe.

Could a bad PCM ground cause issue? They have that grounding tab on the plastic housing... this one did not have that...

Open to any of your thoughts guys... My brain is tired!

 

2000 Cali model excursion, auto trans

 

Do you know what the hell the AP is? I have no idea...

 

Accelerator Pedal??? It uses that for a reference voltage?

 

Vref is +5 volts supplied by the PCM and powers most sensors. The easiest way to measure Vref is at the MAP sensor, unplugged, outer two terminals. With key ON measure voltage and it should be 5 volts. If it is not there start unplugging every sensor, one at a time, until it come back.

 

Yep ...................

 

I have done that before at the MAP so this makes sense. I guess I never really knew they were all tied together on that reference voltage circuit. I will do this when I get home and see what happens.

Thank you again for your help!

 

This is deep... subscribing!

 

I SURE WISH I KNEW A LOT OF ANSWERS TO THIS CRAPSHOOT.

 

I've been reading along, way over my head which doesn't take much though.


Is a lot of that chart apply to our 7.3's?