I just bought a 93 Sedan Deville. The instrament pannel does not work. Also the blower fan does not work. Any suggestions?
Country: United StatesMake: CadillacModel: Sedan DevilleYear: 1993
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Hi and thanks for choosing JustAnswer. I'm Jeff and I'll be happy to help you with your Deville. The IP [Instrument Panel] and other displays not working are a common problem, often the BCM [Body Control Module] is at fault. Along with the IP, the FDC [Fuel Data Center], ECM [Engine Control Module], ECC [Electronic Climate Control] and BCM are connected by a communications link. It's a fairly complex system; for example, to get the blower to work, the ECC sends a message to the BCM, which then controls the blower speed using the ECC Power Module. The BCM is responsible for the power supply that the other displays need to operate, but if they're not all dead it's another issue. GM was nice enough to provide a built in scanner to access different parts of the system-get trouble codes, clear trouble codes, force certain controlled devices to operate for testing purposes-in 1993 it was really quite an advanced system. The following images are the beginning of the 'display panel diagnosis' sequence. To figure out what's wrong with your vehicle it would be absolutely unwise to connect an aftermarket or dealer scan tool-I have not seen one that will provide accurate information. BCM issues are so common it would not be a bad guess to change it, but that is not a simple procedure. It's possible that the IP has a poor connection, but if all the fuses appear ok then this is where a dealer tech would start. If you have any questions please don't hesitate to ask, I'm here to help you the best that I can. I'll be waiting for your reply, Jeff
Jeff, Thank you for your responce. I have been busy and just got a miniute to check responce. With that after work I will check your recomendations. I felt it may have been, BCM but had no idea where to start. will let you know.
Hi Rich, thanks for the update. What you have is the beginning of the diagnostics for a dead display. Overall, diagnostic "flow charts" can be confusing if not intimidating-don't let them scare you. Caddys are GM vehicles but they have advanced systems that are over complicated. Ask me anything that's not perfectly clear. Jeff
hey Jeff, at a stand still. I checked all fuses, I have some of the displays, check engin, airbags etc. What I do not have is the crucial, speedo, fuel, stuff like that. Guessing is ok but the Troopers don't want to hear it. I am mechanically inclined, is it possible for me to change the BCM?
,hey Jeff, at a stand still. I checked all fuses, I have some of the displays, check engin, airbags etc. What I do not have is the crucial, speedo, fuel, stuff like that. Guessing is ok but the Troopers don't want to hear it. I am mechanically inclined, is it possible for me to change the BCM?
Hi Rich. If your Fuel Data Center and climate controls are working we can jump to instrument panel diagnostics. Is this a digital cluster? does the speedo read zero all the time? does the fuel gauge have a flashing "E" displayed? There's a different set of procedures for the two types of clusters, and I don't want to overload you with irrelevant information. Jeffzaphod41090.1467194792
Jeff, Fuel Data center Climate controls are not functioning. There is no speedo at all nor fuel gage. it is blank. When I start the car the check engine light air bag etc. come on then of as they should. Thanks for your time I wish you were local.
Hi Rich; Ok according to the previously posted chart, with totally blank displays [no c or d displayed] we're directed to either chart c1d or c1e, it depends if the blower is off or not. If it's on and you can't turn it off, we skip a bunch of stuff. See the posted chart and let me know which one we need next. If I post both it will most assuredly confuse you. Things are not looking well for the bcm. Jeff
Jeff, the blower does not come on at all. Things are looking awful dim for that poor old bcm. By the way, I just wanted to thank you for the time. I I will after your next responce rate the service, excellent.
Hi Rich; if the blower's dead then we follow this chart, C 1-d: The next image in this chart is the wiring diagram previously posted. By 'backprobing' they mean we insert the meter probe into the connector at the same place the wire goes. This is necessary when checking for an output from a module. Pins make this job easy:if there's room and the probe tips are small in diameter and they fit easily:The BCM has two connectors; one has 24 cavities and the other has 32. These are typically called 24 pin and 32 pin connectors [as are all connectors] even though there may be no actual pins in many locations. Your two connectors with their circuit to pin assignments and wire colors follow:CAUTION! This view of the connectors is the pin side, not the wire or harness side. Some [most Asian] manufacturers tell you this, GM engineers [the, um, nice people who designed all their flow charts and diagnostic procedures] chose not to. Above, as you can see, is the connector with rows A and B, next is the C/D connector:If your voltage measurements call for a BCM, I would try disconnecting the Fuel Data Center [FDC] and Electronic Climate Control panel [ECC] one at a time. With only one of these connected [and nothing else disconnected] turn the key on and see if it 'wakes up'. If it's dead, cycle the key off and try the other. There have been rare instances where one of these was pulling down the 16v supply from the bcm, but not enough to damage the bcm-just enough to prevent any of them from turning on. If you get no reaction, try turning the key on with both the FDC and ECC disconnected>watch the IP for any activity. If anything happens with the IP when both modules are out, one of them or both of them could be the culprit [very, very rare]. There is a rather extensive built in self diagnostic [scanner] system, but the ECC panel needs to be working to use it. Your BCM is here:It's behind the dash on the passenger side, way up high in 'don't cut yourself on those sharp edges' territory. The procedure to get it out, and another illustration:I once tried to put together a list of acronyms in the industry. I gave up. DERM=Diagnostic Energy Reserve Module; it's what most others call the Airbag Module. The 'reserve' means it's got the capability to store enough electrical energy to blow the airbags if, in a verified crash event, the power supply to the DERM is cut off. If you swap the bcm: key is off, battery is disconnected, ["battery cables shorted together" - it seems this suggestion shows up quite often and I can't see why. It won't really do anything like discharge any stored energy for computer memories or in the DERM, but it makes people watching you think you know what you're doing. Plug in the 'new' BCM and flip on the key. Jeff
14+ years on an automotive technical hot line; Top Gun Diagnostician award
Hi Rich, thanks for accepting and the positive rating. Don't forget to let me know how this turns out. Jeff
Hey Jeff, I will let you know how i make out. I am preparing for Bcm surgery Saturday. Thank you again for time and info. I can wrench with the best, but diagnostics...leave that to the big boys.
Hi Rich, Don't fool yourself, it's not that difficult-just go one step at a time. Jeff