Hi forum members, I have had an intermittent no start problems for the last 2 weeks and only called towing once only to find out that the mechanic started it consistently 15 times in a row. I thought it might be the starter but after reading a couple of forum threads I don't think it is. The times it does not start the security light flashes when key in on position. Cleared all old codes and only 1 stays H C and that is 10PCM P1631. What would be my next step? Thanks

 

Sounds silly, but take a pencil eraser and clean the pellet that is in the key. Sometimes will will get coated and not read the correct ohms.

 

Try cleaning your key pellet with a pencil eraser and alcohol. Spray some electrical contact cleaner in the ignition switch. Try another key and see if the code comes back.

 

Is the ignition switch original?

 

I tried erasing both pellets and alcohol on both keys but it has not done it again since but I feel nervous to take it out on an extended trip. I believe the previous owner bypassed the ignition switch with a resistor because of this same problem. Other suggestions?

 

You can bypass the VATS circuit, but you can't bypass the ignition switch itself.

Though now that I look up your code...

P1631 - Theft Deterrent System Password Incorrect

I don't know if that means your resistor (be it inline or on your key) is out of range or not. I'm at work, so I can't get to my service manual, but hopefully someone (Bill Curlee!?) will chime in before then with more detailed data on that code.

 

Could be a number of things, if it's a automatic it could be your Park/Neutral switch, if it's a manual it could be your clutch pedal switch. Next time it fails to crank snake a metal bar or pipe and rap on the starter. A friend of mine traced his occasional no start/crank problem to bad ignition switch contacts, which he just replaced and has not had any problem since. Good Luck.

 

I had the same issue with my 02, and I cleaned the key pellet with a soft pencil eraser and it has never done it again over 2 years time.

 

Is this problem a crank, no start, or a no crank problem?

I have replaced the ignition switch twice, the last time because of an intermittent crank, no start. And in the second instance the mechanic checking the car got it to crank and start every time, several times in a day of trying to diagnose the problem.

A week later, though, additional symptoms including crank, no start, crank and start with "Service Traction System", crank, start and die, crank, start and reduced engine power warning, shut down, crank and start with service engine soon warning.

All fixed by replacing the ignition switch.

 

The flashing yellow "Security" light on the dash and the P1631 trouble-code are keys to the issue. These would not show up if it was a starter motor, etc problem. I'm betting the OP has NO CRANK when this condition occurs.

I had the same exact thing with my 02, and just cleaning the key pellet with a pencil erasure cured it for good. If the pencil eraser cleaning doesn't work, then it could be the ignition switch no reading the key pellet. The P1631 trouble-code is saying there is something wrong with reading the pellet resistance value.

 

From the Owner's Manual ... you know, the book that sometimes has good info.


PASS-Key

Your vehicle is equipped with the PASS-Key (Personalized
Automotive Security System) theft-deterrent system.
PASS-Key is a passive theft-deterrent system. It works
when you insert or remove the key from the ignition.
PASS-Key uses a resistor pellet in the ignition key that
matches a decoder in your vehicle.

When the PASS-Key system senses that someone is using
the wrong key, it shuts down the vehicle’s starter and fuel
systems. For about three minutes, the starter won’t work
and fuel won’t go to the engine. If someone tries to start
your vehicle again or uses another key during this time,
the shutdown period will start over again. This discourages
someone from randomly trying different keys with different
resistor pellets in an attempt to make a match.
The key must be clean and dry before it’s inserted in the
ignition or the engine may not start. If the SECURITY
light comes on, the key may be dirty or wet.

If this happens and the starter won’t work, turn the
ignition off. Clean and dry the key, wait three minutes
and try again. If the starter still won’t work, wait three
minutes and try the other ignition key. At this time, you
may also want to check the fuses (see “Fuses and Circuit
Breakers” in the Index). If the starter won’t work with
the other key, your vehicle needs service. If your vehicle
does start, the first ignition key may be faulty. See your
dealer or a locksmith who can service the PASS-Key.
If you accidentally use a key that has a damaged or
missing resistor pellet, you will see no SECURITY
light. You don’t have to wait three minutes before
trying the proper key.

If the resistor pellet is damaged or missing, the starter
won’t work. Use the other ignition key, and see your
dealer or a locksmith who can service the PASS-Key to
have a new key made.

 

Great suggestions guys, I did not know the 3 minute reset rule. Will that always work? It is a flashing security light in the ON ignition switch position that gives a no crank problem every time but if security light stays on it will start, Hopefully it is just the key,