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no headlights - Chuck_thehammer - 12-11-2010 01:54 PM

2002 Chrysler PT Cruiser, 2.4l Four cyl. Auto, 70,000 miles

last night wife started car to come home and the head lights would not come on... I went to where she was and engine started fine but no headlights and no power door locks or power windows.. everything else works fine..incluiding turn signals and wipers..
I am thinking light switch but what about the power locks and windows?

so we left the car where it was parked for the night and returned this morning and everything is working again? lights, locks and windows...

any IDEA.

Thank You for your Help.


RE: no headlights - Rupe - 12-11-2010 03:59 PM

This is going to be a tough call as the only thing I can think of common to all of these is the BCM (Body Control Module) and they are not cheap. They are also specific to each model and must be programed at installation.... including VIN, mileage, and the various accessories it controls.

Now, there may be a clue hidden in memory that a fancy scaner could pick up. This is not the tool commonly used by the parts stores to read typical engine diagnostic codes. It's something the dealer and some well equiped shops may have and it has the ability to read codes from ALL of the on-board computers, including the BCM. (which may or may not set a check engine light)

A little more about the BCM here.... it's what controls most all of the accessories in the car, including the delayed headlight timer, interior lights and locks with the remote key fob, anti-theft system, parking of the wipers AFTER the key is off, etc. In my mind it's the "better mouse trap" (that needs a 9 volt battery) which is nice to have but can screw up everything when it doesn't work. The bad part is there's no work-around on a failed unit.

On the bright side, because it's interconnected to EVERYTHING it's also prone to bad connections. IOW, if you come up with a code saying communications failure you should try checking every plug you can find under the dash. OTOH, there have been cases where the issue has been a cracked solder joint on a circuit board that can make you pull your hair out. That happened to my personal car 100 miles from home and it seemed ok the next day. (after being towed)

Keep us posted.

RE: no headlights - Chuck_thehammer - 12-19-2010 04:55 PM

Thank you for the information... I did not know about the other computer...

the next day the lights and stuff started working again... NOW I do not trust it.
so if it goes out again. I will look for connectors that may be loose or dirty. other wise it will be off the the dealer (SAD).
Thank you for the information... I did not know about the other computer...

the next day the lights and stuff started working again... NOW I do not trust it.
so if it goes out again. I will look for connectors that may be loose or dirty. other wise it will be off the the dealer (SAD).

RE: no headlights - Rupe - 12-19-2010 05:14 PM

Just a thought and I don't know if the car has this feature....

Some vehicles use a relay to turn off major accessories during engine cranking, which makes it easier on the battery. If you have such a relay it may be worth looking at the pins of the plug or doing a swap with another relay of the same part number. (AC, fog lights, etc)

RE: no headlights - Chuck_thehammer - 01-06-2011 11:41 AM

I looked at a service manual and I could not locate a computer for the lights and door locks... just a multi-function switch next to the steering wheel and a couple of relays for the lights...
each head light has its own relay, so one for the left and one for the right...

I maybe looking at replacing the multi-function switch... big money, not unlike a computer

Thank You and have a better New Year...


RE: no headlights - Rupe - 01-06-2011 12:01 PM

Found this concerning the power locks.

What this tells me is the car does in fact have a BCM, which is a small black box under the dash.

RE: no headlights - Chuck_thehammer - 03-28-2011 05:11 PM

The PT does not have a computer for the lights, just a electronic box for the remote locks... the problem turns out to be the multi-function switch also provides power to the power door locks... I replaced the switch and located the power "in" wire to the switch had gotten HOT and melted the plastic that holds the contact pin in place, also making a loose connection to the switch.

RE: no headlights - way2old - 03-28-2011 08:15 PM

Thanks for posting the fix. Most people forget to do that.

RE: no headlights - Rupe - 03-28-2011 09:40 PM

Yes, also glad to hear the final resolution!

Now that you mention the melted plug I have to ask if you had replaced any fuses. The thinking in my mind is along the lines of these items (locks, windows, etc) may all be supplied with power through a circuit breaker, not a fuse. What happens is there's an intermittent short and the circuit goes dead for EVERYTHING but at times the breaker resets and some of the items work again. (till the next time)

RE: no headlights - Chuck_thehammer - 04-01-2011 05:48 PM

I have not found any circuit breakers but I have not needed to replace any fuses...So I believe the problem has been "OPEN connections" caused after the contacts got hot and lost contact.
I believe the light switch became resistive and heated the pins and wires on the input side and over time became intermittent.

Thank you for all your help.
I think it is a good idea to update posts so others may fix their problems.