ENGINE Crank, No start

AUDI08R8

MEMBER
2002 FORD F-150
V8
4WD
AUTOMATIC
100,000 MILES

I'm an Audi technician and i'm working on my father's truck. It intermittenly would not start, but after letting it sit for a few minutes it would start right up yesterday. Now today I can't get it to start at all. I can not hear the fuel pump prime when cycling the key to on and the theft light is blinking when I am trying to start it. Now on Audi's when the theft light blinks when your trying to start it, it means that the vehicle does not recognize the key. Is that the same with this Ford? And if so how can it recognize the key intermittenly. I've tried his spare key as well but the light still blinks and the truck will not start.

Sunday, October 12th, 2008 AT 9:53 AM

7 Replies

MERLIN2021

MECHANIC
17,250 POSTS

POWERTRAIN CONTROL MODULE Passive Anti-Theft System (PATS) communicates with PCM through instrument cluster to enable or disable vehicle's engine. Within one second after engine start, PCM must receive an enable signal from instrument cluster or engine will be disabled. Along with enable signals, instrument cluster and PCM share messages that confirm security codes shared during initial installation.

This shared security data makes instrument cluster and PCM a matched pair, so neither will operate in another vehicle. When system is functioning properly and ignition switch is turned to RUN or START position, THEFT indicator light will turn on for 3 seconds, then turn off. Vehicle will be enabled to start and run.

If a problem exists in PATS, THEFT indicator light will stay on or flash continuously.

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Sunday, October 12th, 2008 AT 10:13 AM

AUDI08R8

MEMBER
2 POSTS

Thanks for the quick feedback, fuses are all good. I don't understand how the PATS system could just lose 2 programmed keys. However he does need a new battery, and I know low battery voltages can do some wacky things to control modules. Do you think this could be the root cause of this situation? And do you suggest I get a new battery and see if the dealer can reprogram the key?

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Sunday, October 12th, 2008 AT 10:29 AM

MERLIN2021

MECHANIC
17,250 POSTS

Try the new batt first, if lower than 9 volts, PCM does not work!

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Sunday, October 12th, 2008 AT 11:56 AM

AUDI08R8

MEMBER
2 POSTS

Got new battery, still will not start, theft light still blinking

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Sunday, October 12th, 2008 AT 3:12 PM

MERLIN2021

MECHANIC
17,250 POSTS

You will need to have either Ford or a shop that can read and command the modules, it either needs a new RAP module or it needs reprogramming.

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Monday, October 13th, 2008 AT 1:51 PM

ANDREW 02 F-150

MEMBER
2 POSTS

I have the same truck and went through the same ordeal a few weeks ago. The two parts that turn out to bad most oftten are the insturment cluster (HEC) or PATS transceiver. Mine was the PATS transceiver. The info I was giving from my mechanic to diagnose the problem was that if the odometer was showing the numbers as it's suppose to then more than likely the cluster is fine, but if you have - - - - - - or nothing at all showing in the odometer area with the ignition on, then more than likely the cluster is bad. If it is the cluster, only a ford dealer can program the new cluster to communicate with the PCM. Prices for the cluster vary depending on if you want a new or used one. The PATS transceiver is located around the ignition switch. It is a 3 wire sensor that senses the presence of the ignition key. If it doesn't pick up the key it tell the PCM to disable the vehicle. Check for 12v supply voltage and for signal voltage at the wire harness. I bought the transceiver from the ford dealer for $50.00. Good luck. This problem drove me nuts for a few days.

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Saturday, October 18th, 2008 AT 6:35 PM

JJMTUTTLE