My son just bought a 2001 Expedition and it has a number of quirks. We have worked out most of them, but there are a couple I think might be related and might be pointing to a bad/failing RAP module. Just want to see if I am on the right track or chasing a red herring.

Problem #1. Both the driver and passenger side door lock switches are capable of locking all doors. Both switches can unlock ONLY the driver's door. Neither unlocks any of the other doors. The wiring diagram would indicate that this is a bad "unlock all" relay (as the driver door appears to have its own unlock relay). But... all our searching (both physical and Google) has failed to find said relay. We found one post that suggested that this relay is actually a part of the RAP module. I have no idea if this is true or not.

Problem #2. Occasionally, the vehicle simply fails to start, with the theft indicator lighting up. Normally, waiting 5-10 minutes and trying again works. But last night it took 3 hours before the system reset. When it did start, it behaved like a weak battery with a difficult turnover. But unlike a weak battery, repeated attempts got closer and closer to turning over until it actually started.

So, do these two point to a RAP module failure or something(s) else?

 

The lock relay block is behind the right side of the instrument panel. I'm not sure if you can access it by lifting up the oval access panel on top of the dash, but I would try that before removing the cluster. To ID it just put your hand on various components while operating the door locks and you should feel it click.

 

1. The 01 Expy/gators don't have external lock/unlock relays, everything is done inside the Central Security Module itself. It has separate outputs for driving the driver's door lock motor and another for "all the rest". The CSM is located up under the dash on the driver's side, way up there. Look for the large label with the door code on it if keypad equipped.

2. Does "with the theft indicator lighting up" mean that it's fast-flashing? If so, then that is a PATS event and engine operation has been prevented by the PCM (no fuel injectors). Common causes are a problem in the power feed to the PCM and cluster or a failing PATS transceiver ring around the key cylinder. Verify the cluster powers up normally and the digital odometer doesn't read all-dashes and verify the MIL comes on during bulb prove-out, as those are good indications that the PCM and cluster are communicating with each other, a necessity for a successful PATS authorization. IF that checks out, put the cluster into HEC Dealer Test Mode (use google) and see if there are any PATS-related DTCs stored in the cluster.

The two problems are likely unrelated but coincidental.

 

A mechanic friend took a look and believes that it is likely that the problems are all coming from a failing starter.

If that doesn't pan out, we'll take a look at the PATS. We currently have four programmed keys. We tried them all and appear to be seeing the same issue with each. When the engine fails to start, the theft light flickers rapidly rather than simply lighting up briefly.

 

Fast flashing means the PATS did not approve the key. Does it have a slow crank or normal crank? If bad starter or bad battery, in extreme cases the battery voltage might drop enough to interrupt the PATS when reading the key, but then you will obviously have a slow crank as well

 

A more accurate description is needed.

"Flickers" or "fast-flashes"? A "flickering" light would be one that doesn't reach full brightness, no matter what. A "fast-flashing" light is one that rapidly turns on and off, reaching full brightness during each brief "on" interval.

Turn the ignition switch from OFF to RUN (not START) and specifically observe the THEFT light. This completely eliminates the possibility that a failing starter is pulling the battery voltage down and you can get an accurate assessment of the PATS behavior.