QuestionQUESTION: Last week, my 1994 Chrysler Concorde's instrument cluster failed and the blower motor became stuck on high, blowing out a steady stream of hot air. To be precise, the gas, speed odometer, tack odometer, and temperature gauges are all dead (just like the car is turned off (I have Cluster Type C, (see pg. 8E-2 of the 1994 Chrysler Service Manual))). In addition, there is no lights to the A/C Heater Control, it does not respond to any of the buttons, and none of 'idiot lights' come on (e.g. check engine, oil, low gas, etc.). Meaning, I can't even get the check engine light to blink out the error codes because the light doesn't even turn on. These inconveniences, do not hinder the car from being started or driving down the road. Again, to be precise, the lights (both high and low) work, all the turn signals work, dome light works, and the instrument cluster light (that turns on when you turn on the head lights) works. I have checked all the fuses and all are in working order. I have tried two mechanics and they are clueless and expensive. My questions are (1) what should I look at first (powertrain control module (PCM); the body control model (BCM with the bone, gray and black plugs), or the instrument cluster) and is, and for that fact how, the CCD bus is involved in the function of the gas, speed, tack, and temperature gauges, or for that fact, the blower motor and the A/C heater control panel?
ANSWER: Hi W. Jensen,
The power for the cluster function comes from either fuse 9 and fuse 17 in the box behind the left endcap of the dash so I would check those for function (they may look good but can have a subtle crack in the internal wire). The heater/ac control fuse is #6 so check it similarly with a volt/ohm meter. The blower running on high only usually is the sign of a failure of the blower motor resistor block (assuming this is a conventional control) of the blower motor module (if this is a automatic temp control). But the loss of lighting at the control should be remedied first before concluding it is the block/module.
I wouldn't get into the digital issues until I was thoroughly satisfied that I had power to the cluster pins and the ac control pin (pin 6 and 8 of the black plug at the cluster, pin 5 of the blue plug at the ac/heater control, check with the key in the run position). Let me know what you find and we'll go further.
Roland
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QUESTION: Fuses 6, 9, and 17 are all good, using the ohm side of the meter. I checked the voltage for each fuse. Keep in mind, all the fuse plugs are vertical. The descriptions for each fuse comes off the black plastic cover, found on the left side of the inside of the car, that covers the fuse panel.
Test results...
Fuse#06 = 10a Heater - A/C ATC
With the key off, noting.
With the key on, the meter shows 12.27 volts only on the bottom fuse plug.
Nothing on the top fuse plug.
Fuse#09 = 15a Illum Lamps - Park Lamps
With the key off, the meter shows 12.25 volts on the top fuse plug.
Nothing on the bottom fuse plug.
Fuse#17 = 5a Gauges - P R N D L
With the key off, noting.
With the key on, the meter shows 12.18 volts on the top fuse plug.
Nothing on the bottom fuse plug.
What's next?
ANSWER: If one side of a fuse shows 12v compared to chassis ground (any shiney metal surface of the body) then the other side has to show 12v unless it is blown out. It seems contradictory to me that you say that you tested the fuses by ohm measurements and found them good (did you remove the fuses from their sockets?). So please look again in that manner.
---------- FOLLOW-UP ----------
QUESTION: Allow me to clarify, the fuses were pulled checked for continuity. All the fuses are good. With the fuse removed, a meter was used to see if there was any voltage going to the fuse plug in question. As described above, the three fuse plugs all had power and we now know which side of the fuse plug the power comes into.
AnswerThen check the pins at the plugs of the ac/heater control and at the instrument cluster for 12v that I referenced, and also verify that the black wire on any of those plugs is indeed 0 ohms to ground. If the basic power circuits are thus found to be good, then the units that they control are in question. By the way, is this an automatic or conventional temperature control type unit?
The ccd bus is needed for the gauges to operate and for the ac control to function so that is the next step. The fact that the blower control and dash went out together suggests that is a distinct possibility. Have you tried for fault codes using the ignition key? On-off-on-off-on and leave on, doing that in 5 seconds or less elapsed time; then count the flashes of the check engine lignt if will flash, pause, flash, etc. Tell me the counts in order of appearance. Finally, also check fuse 14 in the dash fuse box as that powers the BCM which may be involved in the ccd bus performance question. One possibility is that the ac controller has failed (based on lack of lights/blower control) and that took 'out' the bcm communication to the cluster. You might try pulling the plugs on the ac control and then see if the cluster starts working again.
Another possibility, if this all began after a car wash or heavy rain, is that water leaked down from the windshield onto the top of the bcm and shorted out the ccd bus wires. If that were the case you could remove the 3 plugs and spray the sockets with electrical contact cleaner which will evaporate any water residue.
Roland
PS Please rate my answer and where you see the question about 'volunteer of the month' consider a 'yes' answer if these responses prove helpful. Thanks
