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Chrysler Repair/'98 300M ATC unit non-functional


QUESTION: Hi Again Roland,

This is a followup on my efforts to fix my friend's 99 300M.  
Didn't have much luck with the eBay unit that was missing a button (the screen would not light up) but at least they didn't charge me for it.  Ordered a rebuilt one from eBay, but it gives the same symptoms as the old controller i.e:
1) Hitting the off button makes the unit shut down, then start back up on its own a few seconds later.
2) Temperature Display is simply two dashes (- -), and temperature up/down buttons have no effect.
3) Diagnostic never completes.

So, it would appear to be outside of the control unit somehow.  Either that or the problem instantly breaks climate controllers ;-) any more ideas to check?

ANSWER: Hi Gereon,
The only suggestions I would have are first to remove the fuse 19 (the ignition off draw fuse which will erase fault codes from the BCM) from the dash fuse box for 5 minutes then start the car and see if the unit will self-recalibrate and run any differently; and get a fault code readout of the body control module via the data link connector under the dash near the steering column to learn if there are any 4-digit fault codes preceded by a B. Let me know the results of either of those approaches. Does the friend know of any relevant 'history' to this problem? No one has raised it before to me.
Please 'rate' my answer (see the PS below).

---------- FOLLOW-UP ----------

QUESTION: Thanks Roland!

Pulling the fuse did the trick, at least for now. I pulled fuse 17(Heater A/C ATC) and 19(Interior Lamps). Everything seems normal and I get no codes from the button test.  I would have checked for codes beforehand but I misplaced my code reader and didn't find it until later.  If the problem returns, I'll try to get codes.

Hi Gereon,
Hey, that is great news. I found that suggestion in the '04 manual for the 300. Let me know if it doesn't 'hold'.
Thanks for the nomination as well. With your help I tied for "Top" in February and today's gives me a good start for March.

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Roland Finston


Get a Free Fast answer to your repair question about a Chrysler/Dodge/Plymouth car, minivan, SUV, or truck. Problems with electronically controlled engines and transmissions as well as body wiring problems are my specialty. This free troubleshoot advice forum helps you diagnose faults, minimize repair costs or do-it-yourself.

I answer questions seven days a week and respond to you in about 30 minutes. "Maxed Out" means I am answering another question, briefly unavailable, so try again later.

I have do-it-yourself experience (50+ years) and a library of 100 1982-2012 Chrysler factory shop manuals and 20 multi-manual Chrysler Corp. CD's.

I was voted "Top Expert" 2010-2015, here at AllExperts, and have answered 20,000+ questions.


Five decades as a 'do-it-yourselfer' on domestic and imported cars.

Yahoo Autos Group called The Chrysler Lebaron Club (co-moderator)

Advanced degrees in Physics/bruised knuckles

Awards and Honors
"Top expert" of 2010, 2011, 2012, 2013, 2014 and 2015 here at Allexperts. Quickest "average response time" at Allexperts (currently no. 1).

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