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Tim Mohr
Tim Mohr, ASE MASTER TECH
Category: Chrysler
Satisfied Customers: 15583
Experience:  30 YRS EXPERIANCE, AUTO AND TRUCK,FOREIGN AND DOMESTIC, GAS AND DEISEL
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2001 Chrysler LHS. Blower motor inoperative and the ambient

Customer Question

2001 Chrysler LHS. Blower motor inoperative and the ambient temp reads -40. Have power and ground to blower motor control, but no signal from BCM. When looking at BCM data, the blower shows off no matter which position the ATC is set at. Tried a new ATC, Blower motor and Blower motor control. Also a new ambient temp sensor.
JA: Have you checked the connectors on the sensor itself? It's important that they not be loose or corroded. Are you hoping to fix this yourself? What have you tried so far?
Customer: I have checked the connections. all seem fine. I am trying to fix myself. See above post for what I have done so far.
JA: Anything else you think the mechanic should know?
Customer: The car belongs to a friend of mine. He says it all started when they had an aftermarket radio installed. I have since reinstalled the factory radio, with no results.
Submitted: 11 months ago.
Category: Chrysler
Expert:  Tim Mohr replied 11 months ago.

Hi, my name is ***** ***** the default temp, when there is an open in the wiring from the ambient temp sensor, so they most likely damaged the wires when putting the radio in, or hooked a wire from the sensor to one for the radio, have you checked the wiring near the radio?

Customer: replied 11 months ago.
I have. I have also reinstalled the factory radio. They did the install correctly, (using the proper harness adapters). They only thing that I did see is one small black wire going to the ATC is bare in one spot and had tape over it.
Expert:  Tim Mohr replied 11 months ago.

That is a ground wire, which cnnector is this black wire in?

Customer: replied 11 months ago.
It is in the connector for the ATC.
Expert:  Tim Mohr replied 11 months ago.

how many wires are in the connector? 4 or 9?

Customer: replied 11 months ago.
I believe 9. Definitely more than 4. The car is at home, I am currently at work. All other functions of the ATC work (blend door, mode door, etc.) Just no blower at all.
Expert:  Tim Mohr replied 11 months ago.

ok, this is the ground wire for the atc, and it needs to be grounded, they most likely cut this wire and used it for a ground for the radio, you need to ground this wire to any bare metal, and the blower should work, Tim

Customer: replied 11 months ago.
The wire is not cut. Just bare in one spot. I will recheck it, but Im pretty sure it has a ground. There are 2 grounds going to the ATC according to the wiring schematic that I have. I will recheck it though. The radio was grounded through the braided ground strap, but it is possible that they tried to tap into the black wire first.
Expert:  Tim Mohr replied 11 months ago.

that what it sounds like, check that wire for a good ground,Tim

Customer: replied 11 months ago.
I will check and give you an update.
Expert:  Tim Mohr replied 11 months ago.

let me know,Tim

Expert:  Tim Mohr replied 11 months ago.

Please dont forget to rat e, so I can get credit for helping,Thanks,Tim

Customer: replied 11 months ago.
I have checked the black wire, and it does have a good ground. I did however hook another good ground to it just in case. No results. I removed the ambient temp sensor again and checked the terminals etc. One thing I did notice is that with it unplugged, the PCM throws a P1478 code and the battery light comes on. If I plug it back in the battery light as well as the check engine light goes out. This tells me the ambient sensor may not have an open circuit, but maybe a communication problem between the PCM and BCM? Can I purchase a used BCM with the exact same part number and just do a swap? or do these need to be programmed by Chrysler/Dodge?
Expert:  Tim Mohr replied 11 months ago.

It would need to be programmed to your vin number, after installing it,Tim