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1987 DeVille 110000mi

Analog speedometer quit working (I've seen this before but it always started working again) Smoke from accessory side of engine.....smells electrical.  Can not locate where it's coming from/no smell in cabin).  FDC/CCP worked a few days ago when I pulled codes E13 and some BCM codes having to do with the bad AC compressor.

Today the FDC and the CCP is dead.  All the panel segments illuminate w/key ON and car starts/runs well.  Stumped.  Can use some advice, thanks

Dave

Edited by Dave in Texas
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GM Reman 4.1 engine Dec '08

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Did smoke from the engine belt area and A/C happen at the same time? That sounds like an A/C clutch failure but that should not affect the CCP or the FDC.

Something burning and the speedo inop could be a VSS wire shorting on the rear exhaust pipe ...... ( maybe - it does happen ) .... ??? By the way the speedo, even though it is analog is not a mechanical driven speedometer it still translates VSS signal to give an analog indication.

You say all the panel segments illuminate, so, with key on - eng off - do the panels display normally? Can you retrieve codes with the engine off? Do you have a FSM for the vehicle?

 

Edited by OldCadTech

THERE IS ALWAYS ENOUGH TIME TO DO THE JOB RIGHT - THERE IS NEVER ENOUGH TIME TO DO THE JOB AGAIN !!!

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Thank you for your response.

No, the AC compressor has been disabled by the computer due to low pressure.  AC compressor has been leaking at the front seal for some time.  Wiring still plugged in but I figured is the computer won't let the clutch engage nothing bad will happen. I've been waiting for cooler weather to change the unit and repair the system.  (That compressor is 18yrs old and I've sure gotten my monies worth from it.  I rebuilt the system in '98 and changed to R134a)

I've had a new speed sensor on the shelf for some time....guess I'll get after that too.  I'll try an trace that wiring down as well.  Also have a new/rebuilt BCM on the shelf for the justincase scenario.

Problem with the displays was solved today....blown fuse.  New fuse brought everything (FDC/CCP) back to life, but I'm concerned why the 20A fuse blew(#16).   Retrieved some E codes but no F codes displayed..

Yes, have FSM for it.  First thing I bought after driving car back to Texas from Fla.

Thanks for the help, I really appreciate it.

Dave

 

 

GM Reman 4.1 engine Dec '08

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I agree, your A/C problem is probably unrelated to the electrical problem.

Have you done any repair work or replaced any components that may have disturbed/moved any wiring looms in the engine compartment?

Look in the electrical section of the SM and try to determine what the 20A #16 fuse powers besides the CCP &FDC, then you can trace those wires and hopefully it will lead you to your burning electrical "smell". If you have trouble translating the schematics post them here and we can help.

THERE IS ALWAYS ENOUGH TIME TO DO THE JOB RIGHT - THERE IS NEVER ENOUGH TIME TO DO THE JOB AGAIN !!!

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Well, hmm...

I've looked at the circuit diagrams and I doubt #16 has anything to do with issue.  The fuse panel is 'upside-down' and #16 is on the first row.  All circuits on #16 are within the car interior.  The 20A blown fuse was not on the first row of fuses>reading from closest to the driver with fifth row being closer to the engine compartment.

More likely it was #7 which is the AC/FDC/CCP/cluster?/defog relay.  #7 circuit goes to the AC clutch and is HOT only in RUN. Haven't run the engine since finding the blown fuse.  I wasn't looking for what wasn't working other than the displays. (cluster....meaning maybe digital cluster?  no got)

Prior to the annual inspection I was attempting to replace the O2 sensor from the engine compartment.  Tried getting some penetrant on the sensor, but could not control the spray in the direction I wanted.  That spray went more toward the belt side of the engine.....somewhere.  Finally gave up trying to find any socket/extension/etc combination to loosen the sensor. Then started the engine.......THAT was when I first noticed the smoke.  Thought nothing of that at all, figuring the Liquid Wrench spray probably landed on the rear-bank exhaust manifold.  Closed the hood and the next day went in for the annual inspection, which was when the inspection guys also noticed the smoke..He/they thought the smoke might have been the AC clutch.  I told them 'probably not since the AC wasn't engaged' due to the computer sensing Low Refrigerant would not let it turn On.

Anyway, the O2 sensor problem remains at issue. The only way to access it is from under the engine with a closed-end 7/8" wrench.....btdt....hate/too old to be laying on the concrete anymore.

Will trace wiring to AC compressor and see if problem is somewhere along it.  Maybe not for a few days tho....24° now and will be too cold(for me) until the 20th.  Being a retired electrician I tend to trust fuses, especially blown fuses, so will not run engine until I can trace the clutch circuit wiring in the engine compartment.

One of the E codes was E47 (BCM to ECM date problem) which I hope was having to do with the blown fuse controlling the CCP display.....

Electrical problems are always a detective story....

Dave

GM Reman 4.1 engine Dec '08

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Dave,

OoO The plot thickens :)

When it warms up !!!, raise the vehicle as high as you can safely raise it and use sturdy jack stands to support it by the unibody ( NOT the engine cradle ) use wood between the stand and the unibody as the lift point tab/lip will usually roll if you don't . Loosen but do not remove the the front 2 cradle bolts ( leave at least 3 turns of threads )  then with a floor jack under the rear of the cradle remove the 2 rear cradle bolts. lower the floor jack being careful not to disengage the steering rack from the column. It's not the end of the world if it disengages, you can mark it before you lower the cradle if you are worried about it. This should give you enough room to access the O2 sensor. I have no idea what your tool box holds but I have removed the AIR management valve assembly from the rear valve cover and used a crows foot on a swivel adapter, extension, breaker bar/ratchet etc. to remove the sensor.

Look at the A/C clutch connector/wiring and make sure it is not damaged I have seen bad pulleys slice into the connector and short it out. 

Stay Warm,

John

Edited by OldCadTech

THERE IS ALWAYS ENOUGH TIME TO DO THE JOB RIGHT - THERE IS NEVER ENOUGH TIME TO DO THE JOB AGAIN !!!

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I'll get under it later this week and replace the sensor.  Access problem has to do with a small air-tube feeing though the firewall....with the angle of the sensor and that tube, getting some leverage on the sensor is a problem.  I have two different tools to loosen/tighten the sensor, just can get the leverage.

Will let you know what I find with the wiring when I find the problem.

Thanks

Dave

 

GM Reman 4.1 engine Dec '08

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