How do I diagnose intermittent crank, no start caused by PATS?

[RussAdams]

My 1999 4.0 OHV 4x4 automatic is intermittently doing the PATS flashing THEFT crank/no start dance. It does not seem to make a difference if I put the key in slowly or fast when it shows the fast flashing THEFT light when it's acting up. The truck does start, eventually.

I've been reading all the threads I can find about this, but I am not sure exactly how to diagnose which part is failing.

The truck has over 240,000 miles and the ignition switch is quite warn/loose when I insert the key. LOADS of play.

How do I go about diagnosing which part is bad?

1. Can the ignition switch slop cause this? How do I tell if it's the ignition switch slop?
2. Is the PATS Ignition Immobilizer Module/Transceiver bad? Can it work only intermittently? How do I tell this is the problem?
3. Is the PATS module itself?

I did find and read Jim Oaks' great article. I just am unsure how to proceed.

Is there a good HOW TO on using Forscan to read the PATS error codes?

Thanks so much for any advice.

Russ

 

[2011Supercab]

Turn on the key and leave it on

Rapid flashing THEFT light will flash for 45-60seconds and THEN start to flash a trouble code, 2 digits with a 1 and then 1 to 6 flashes

11 Transceiver [transponder coil] not connected, or there is no power to it.
12 Transceiver internal fault.
13 No Key/no PATS key has been used to turn the ignition switch.
14 Incomplete key code received.
15 Invalid key code received.
16 CAN communications error.

 

[Curious Hound]

I had just pasted those instructions into my response, when I saw Supercabs response pop up. Start with that and let's find out what codes are showing.

The intermittent nature of your problem makes me think you may have a loose connection somewhere.

The ignition cylinder activates the ignition switch by pushing a rod that pushes on the ignition switch further down the steering column. I would not expect a worn ignition cylinder to cause this problem unless it is so bad that it isn't pushing the rod far enough to properly activate the ignition switch. If that were the case, you should have a bunch of other intermittent electrical issues. It is possible for the harness connector to be loose or partially seated at the ignition switch. Check for that.

It would be good to ensure the harness plugs are firmly seated at the PATS tranceiver and control module.

 

[RussAdams]

Turn on the key and leave it on

Rapid flashing THEFT light will flash for 45-60seconds and THEN start to flash a trouble code, 2 digits with a 1 and then 1 to 6 flashes

11 Transceiver [transponder coil] not connected, or there is no power to it.
12 Transceiver internal fault.
13 No Key/no PATS key has been used to turn the ignition switch.
14 Incomplete key code received.
15 Invalid key code received.
16 CAN communications error.

Great!

I was not aware the THEFT light will flash codes. I'll look for that the next time it happens.

 

[RussAdams]

I had just pasted those instructions into my response, when I saw Supercabs response pop up. Start with that and let's find out what codes are showing.

The intermittent nature of your problem makes me think you may have a loose connection somewhere.

The ignition cylinder activates the ignition switch by pushing a rod that pushes on the ignition switch further down the steering column. I would not expect a worn ignition cylinder to cause this problem unless it is so bad that it isn't pushing the rod far enough to properly activate the ignition switch. If that were the case, you should have a bunch of other intermittent electrical issues. It is possible for the harness connector to be loose or partially seated at the ignition switch. Check for that.

It would be good to ensure the harness plugs are firmly seated at the PATS tranceiver and control module.

Thanks! I'll check the connections for sure. Can you point me to a schematic that shows the rod?

Russ

 

[Curious Hound]

Thanks! I'll check the connections for sure. Can you point me to a schematic that shows the rod?

Russ

I don't have anything handy. If I go over to my house tomorrow, I'll take pictures. I jave 3 steering columns standing in my living room at the moment. But, it's not complicated. You should be able to see and get your hands on the switch. It is on top of the column, just behind where the ears are for the column mounting bolts.

 

[alwaysFlOoReD]

These pics are of a 93 ranger. You can see the rod running down the top of the column to a recepticle. That is the actual switch location.

 

[Curious Hound]

These pics are of a 93 ranger. You can see the rod running down the top of the column to a recepticle. That is the actual switch location. View attachment 148179View attachment 148180

Thanks. Saved me a 4 mile trip on a busy day.