Question Hello,
I have a 1994 Chrysler LHS when I crank it up all gauges(fuel,temperature,oil,speedometer,and tach work as they should.After between 20 seconds and 35 seconds,or so, all instruments drop out (go dead) and the heat comes on ,defrost only,low speed and the air bag lite in the middle of the dash lites up, also the lite on the defrost control button comes on and you cannot turn it off, or change the heat to blow out of different vents. Another words you lose all control over the heating and A/C systems.Problem occurs every time you start up the vehicle, but vehicle runs fine otherwise.
Any advice would be greatly appreciated.
Thanks,
Bennie
AnswerHi Bennie,
That is an interesting confluence of systems that are impacted simultaneously. There are some common wiring paths that impact all of them. One is the collosion data bus which is a digital data carrying system that connects all three (instruments, air bag, automatic temp control) but it also is connected to the body controller, the trans controller, the engine controller so if those are working o.k. I doubt that it is caused by a problem with the bus.
There are two fuses you might want to look at, though they are not involved with all three but one of them #14 is powering the body control module which is one of the brains of the system. So look at that one to see if it is firmly in its socket, after you remove it and look carefully at the wire inside for a possible hairline crack which opens the circuit when current flows thru it. Also take a look at fuse #13 for similar crack or looseness in the socket.
But the one other wiring aspect is the grounding of those 3 units: all go to a common ground at the airbag control module which is hidden at the very bottom of the center console stack of units under the dash (radio, ATC, etc.). To get to it you may have to disassemble some of the lower part of that console. You should find one point where 9 black/light green wires come together and are tied to a bolt attached to the body. If that was not a good firm connection then the grounds for those three units might be flakey and cause the malfunction you are experiencing. If you have trouble finding it, let me know and I can describe how to get to the air bag module, but tell me whether you have the 5- or 6- passenger body which determines how to get to it.
If none of these checks work, then perhaps a visit to a Chrysler dealer to have the collision data bus checked out via a diagnostic readout box might reveal what the fault is with those three unites.
Please let me know what happens as you try to resolve this one.
Roland
