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PATS module "in use" during engine running?

R

Ray

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Jul 10, 2001
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Okay.. I feel awkward EVER posting anything troubleshooting related. very.

Here is my question.

Can anyone fill me in on the state and role of the PATS module and associated wiring (etc) once the car is actually running? I understand the ability of the module to prevent starting, but once started does it still continually check for the correct key? For example: If I were to saw off the black fob on the end of the key while running, and remove it from the ignition vacinity, would the car die?

If not, can anyone fill me in on what the PATS status LED SHOULD be doing while running (off at all times while running, right??) what about a list of PATS status flashes, and meaning? (codes, "all good" flash counts, anything!)

Starting just today, I am getting a very serious BUCK/SURGE (imagine cruising at 10 or 15 mph in neutral, then placing car in first and DUMPING the clutch out. that "grabbing hard and surging" feeling is what I am experiencing. usually sparse, and not affected by load, gear, rpm, or speed (the surge/buck is as violent at 60mph as it is at 30) Sometimes the Tachometer needle will fall instantly (like you shut the car off) by about 500 or 800 rpm, but the engine tone is not dropping..

The reason I ask about PATS is that the instant it does this, the pats LED illuminates and remains for about 1 second (steady) then goes off. If, per chance, the bucking is closer together, then the PATS light flickers, then the last one is steady (as if its doing it once per "bucking") Is this a failing PATS?

No problems starting car... no problems idling. nothing! Just.. bucking. I looked at the plugs and wires, and all is copacetic. If it was spark, I would think it would be more violent at high load/low rpm, or at LEAST able to be affected with driving style!

VSS affect running condition of the car? I think not.
Fuel? full tank and newer pump!
spark? nice plugs and new(er) wires
air/vacuum condition would seemingly cause more precise and localized (by speed/rpm, or at ALL times, even idle)

What say the collective brains of CEG. Those that can help, thank you. those that can not.. listen up so that you can help the next guy with this problem!
 
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Ray,

Sounds like a ground to the PCM, or the PCM itself.

Check the ground strap from the pcm plug to the fender. Check the secondary ground wire that I added when I first installed the emanage. It should go from the pcm wire loom to the firewall where the ground strap from the RH engine mount is screwed in. IF this is broken or corroded it may cause the issue.
 
No findee anythingee, so I guess not.

It is definitely SOMETHING electrical.

the CEL flickers (FAINTLY)
the pats light illuminates for 1 second (the typical thing when you FIRST turn to key on)
The tach "sputters" downward as if power has been removed from the circuit (speedo remains constant)
No other lights come on. charge light, airbag light, etc all stay off.
These happen once per "surge".

There may be one surge or a fit of ten or more, then a break for "who knows how long". I drove to town (miles) with no problems. Drove home with 2 surges. Idling at the store between the to, it had a fit.

I checked the PCM ground and additional loop.
I checked PCM fuse(s) to make sure they aren't loose.

Wonder if the PCM power relay could be "floating"? wouldn't that be the same as removing the PCM ground rapidly, if it were to float/fail intermittently? The soytch continues.
 
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I don't have access to my PID charts (and wire colors) anymore but what are some of the PID values?

Now, my guess is a cross-feed between/within the the tachometer, CEL and PATS wiring.
 
Just as a fill-in.. the problem was solved. It was a faulty TPS/TPS connecter (which of the two I don't know)

It was causing an intermittantly grounded VREF signal. That signal provides a reference to the rest of the car for what "+12V" looks like. Its essentially showing "hey.. this is a known good 12 volts.. anything out there that uses 12V, and needs to make sure it is ACTUALLY 12 volts, compare it to this"

Well.. the signal was grounding out.. and among the things that use VREF are the TPS, the PCM, etc, etc, etc.
 
The connector itself looked "fine". I was experiencing the "stumble" problem, and popped the TPS connector off.. the idle smoothed out, and I replaced the connector on the TPS, never to have the problem again.

There was a "little" corrosion on the pins on the TPS, and that was cleaned, so it could have EITHER been corrosion, a faulty connection, or a shorted pin/bent pin that was straightened out once I pulled the connector and inspected it, etc.. the short could have been made by conductive corrosion between the pins as well, and that would have been remedied when I cleaned the corrosion.
 
Im gonna start sending you Houma guys a bill for helping you all the time :)

Pretty soon ill have enough for a months rent :)
 
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