Chrysler Repair: 94 LHS Electrical Issues


Question
QUESTION: Hello Roland,
         Here are the answers from your questions last night:

The pulsing of the blower motor goes in 1 sec intervals.. on. off, on, etc as long as the ignition switch is on. If the BCM is disconnected, then the blower runs on high when the ignition switch is on. Can not turn the unit off when it is doing either one of these things.

Right now the only gauge that I know for sure that is not working is the gas gauge. Since the car will not stay running the I cannot check the Tach, speedometer or the water temp.

You know about the trans selector lights and the wipers were not working last night either.

Somewhere along the line you asked about the fuel pump for the not starting issue, I hear the pump kick on and I smell gas if I switch on off a couple of times so it appears that gas is getting to the motor.  The car tries to start and will actually sound like it has started enough that you release the key but it does not fully catch and keep running. Could it be the throttle position switch, cam switch or one of the switches on top of the transmission?

Thanks for your help.

Mar

ANSWER: Hi Mar,
Let's focus on the ignition switch outputs. With the key in the "run" position there are 4 separate wires that become powered with 12v. Verify that the following fuses all show 12v: #17, #14, #10, #7. Maybe this will explain some of the issues.
Does the Check Engine light not illuminate on the cluster? That light is needed to do a fault code readout to figure out why the engine won't catch and run.
Roland

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QUESTION: OK I will check those out this afternoon when I get home. The Check Engine light does come on when the switch is turned stays on for what seems to be the normal amount of time and goes off. I do the key to pull the codes and I get nothing. Not even the 55 code that shows no codes and I have always gotten at least that when I have done it in the past.

Mar

ANSWER: I will be interested in your results. It seems as if the digital communication from either or both the pcm and bcm are compromised. But why is still unknown.

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

QUESTION: Hi Roland,
         Here is what I got on the four fuses:
# 17 - 23.9 volts

# 14 - 20.8 volts

#10 - 0 volts

#7 - 18.8 volts

I pulled each fuse and checked thru the contacts instead of thru the  check points on the fuse. BCM was connected.

Mar

Answer
Hi Mar,
Interesting result, in that the voltage of the battery should be 12.4V or so, but that could be your meter in error. The lack of voltage on fuse 10 would explain why no windshield wipers, no radio, and no turn signals. Those other functions are on fuses 2 and 3 so verify that those are "cold" also. If so, then it suggests one section of the ignition switch is faulty.
But, it would not explain the failure to start, the instrument panel, the check engine light not working, etc.
I lean toward there being a module which is part of the digital communication system being faulty such as to cause the failure of the digital communication. One way to check that would be with a Chrysler code reader which means towing to a dealer, or a similar well-equipped garage. An alternative approach would be to try disconnecting, one at a time, each of the digital modules and seeing whether when done the instrument cluster works again/the car will start and run. If any one of them produces that result it suggests replacing that module.
The parts to consider: air bag control module, overhead travel info module, anti-lock brake controller, transmission controller, instrument cluster, body computer, and finally powertrain controller. So that is probably what you do next, after verifying the other fuse sockets I listed.
Roland