I did a little research, and the most that I can come up with is a possible cluster fault, or a possible UART data line fault. You did not make mention on the airbag light, the request for that is an input to the IPC. The park brake switch is an input to the IPC, from there I believe a buss message is sent to the A/C programmer, although I could not find information to support this, it could also be a mechanical vacuum switch on the shifter. The fuel level, which at first you mentioned was inoperative, but have not mentioned, is an input to the cluster. The battery charge is an input to the IPC as well. What defines A/C not working, is it that the blower does not work, the compressor does not come on when requested, the display is blank or shows dashes, or is non functional? A/C information from the cluster is via data line to the programmer. As far as the door locks, I have yet to find any operational, or electrical diagrams that explain who sends the request to lock the doors, it too could be a data line message sent to perhaps the keyless entry module. So you have some common denominators, but I am not saying it is a faulty IPC. On the lights/chime, etc. There is a lights on input to the chime module from the headlamp switch, the IPC can also control the chime module. If it only occurs with the headlamps, it would tell me that the chime module may not be getting ignition power, there pops in that circuit from engine compartment fuse A3. That is where I am in suspicion. You say the fuses have power, and are good, what method of checking have we employed? The reason I ask, is that fuse A3, or the circuits from it, are to me a smoking gun, and this is why. Fuse A3 supplies key on(ign) power to: The low pressure a/c switch(it can prohibit compressor operation), the chime module(ign power only, still has B+ so in theory still powered, i.E. False key off lights on condition), the airbag module(airbag light), two ignition feeds to cluster(possible fuel gauge/charge), through prndl switch to keyless module(door locks), the headlight switch, on the same circuit as the chime module. It just has all the ingredients to be causing the issue. Knowing that, you are going to have to do some teardown, and electrical checks of those circuits to isolate this any further. Tell me this in you next reply, do you have backup lamps, and cornering lamps. The backup lamps are self explanatory, cornering lamps if you are not familiar, are the clear bulbs in front, that illuminate when a respective turn signal is activated. There are some who have not known of the cornering lamps, and to avoid a return post that reads, 'what are cornering lamps?', I thought I would include that info for reference.
Wednesday, October 27th, 2010 AT 10:47 PM