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physics-1
physics-1 6/5/2011
1995 Mercury Grand Marquis LS 8Cyl4.6L - Body & Interior
Possessed electrical system, 1995 Grand Marquis.
The car seems possessed: horn toots, no lights work, cigar lighter no go. Most but not all problems can be linked to the LCM.
We had the LCM rebuilt. Nothing changed.
I bought the Electrical and Vacuum Troubleshooting Manual, FCM-12118-05. What I discovered is that there is no reliable voltage going to the small I/P fuse panel block depicted on the lower left of page 13-6 of the manual, fed by wire 38, which is BK/O (black with an orange stripe).
However, at the engine compartment fuse block, the Lamps fuse, 40A, which feeds wire 38 BK/O, does have 12V. I tore apart both the interior and engine compartment fuse blocks and the wires have integrity. According to page 13-6, between these two is a connector, C224 M & F. Looking at page 151-4, sector E10, C224 should be on the bottom of the connector bracket. In my particular car, however, it is not, instead, it is where C212 should be. But that's no big deal. What is a big deal is that there is no BK/O which travels through
4 Answers
  • HouseCallAuto
    HouseCallAuto 6/5/2011

    1. Check fuses 4 (15 amp), 8 (15 amp), and the 20 amp circuit breaker at fuse holder 12 of the instrument panel fuse box to verify all are present, good, and all have power even with the key off.

    2. If there is no power at any of these fuse holder positions, check the 40 amp LAMPS FUSE PANEL fuse of the engine compartment fuse box to verify it is not blown or missing and that it is making good contact to its holder and has power.

    3. If the 40 amp fuse checks to be ok but there is no power to the instrument panel fuse box fuses, pull the engine compartment fuse box and inspect its bottom side for a corroded or lost connection of the Black/Orange (BK/O) wire which attaches to the fuse holder. Run a new circuit from the engine compartment fuse box off of this fuse holder to the instrument panel fuse box to bypass the open in the circuit as necessary.

    4. If the instrument panel fuse box fuses show to be ok and all have power, check all power supply circuits at the LCM before condemning it as a faulty replacement part.

    A. An Orange/White (O/W) wire feeds the LCM at pin 16 of the C2029 connector from the 20 amp circuit breaker. This is the headlight input feed.

    B. A Light Green/Yellow (LG/Y) wire feeds the LCM at pin 11 of the C2029 connector from fuse 8. This is the courtesy lamp input feed.

    C. A Tan/White (T/W) wire feeds the LCM at pin 6 of the C2029 connector from fuse 4. This is the parking light input feed.
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    HouseCallAuto
    physics-1 6/6/2011
    I had already done steps 1 & 2, as well as 3. What I didn't do was "Run a new circuit." Here's the reason.

    The manual indicates that there is a connector, C224, which should be under the RH IP. It IS there, but there is no BK/O wire at that point. My real question is... Where is this wire 38, BK/O routed? I need to find the connector which carries it between the engine compartment and the interior.
  • CVO
    CVO 6/6/2011
    physics-1 6/6/2011
    I had already done steps 1 & 2, as well as 3. What I didn't do was "Run a new circuit." Here's the reason.

    The manual indicates that there is a connector, C224, which should be under the RH IP. It IS there, but there is no BK/O wire at that point. My real question is... Where is this wire 38, BK/O routed? I need to find the connector which carries it between the engine compartment and the interior.
    Reply
    0
    CVO
    CVO 6/6/2011
    Mr physics-1. Re-post in the "answer question" section, in order to get to a message to Master HouseCallAuto .
  • HouseCallAuto
    HouseCallAuto 6/6/2011
    I see the BK/O wire in pin 8 of the connector view. It enters as a BK/O and leaves as a BK/O. If you are saying that the pin 8 slot is empty then I have no idea why, but maybe, hopefully at worst, the wire was cut on both sides of this connector and rejoined outside the connector? Someone thinking it was not making a good connection and did a bypass? I rarely could say in my 30 something years of this business of repairing cars that the manufacturer made an error. There is likely some reason you cannot find this wire. verify that you are really looking at connector C224. this connector has 8 pins on each side. the BK/O wire is one of the two corners closest to the key-way on the longer sides.
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  • physics-1
    physics-1 6/7/2011
    Yup, the connector I'm looking at has 8 pins on both sides. Only four of them are filled. BK/O is simply not there.

    In that bundle of four connectors, where C224 is, RH IP, there is no BK/O wire at all. Nowhere to be seen.

    My mom owned this vehicle, bought it new from the dealer, so I know the history of this vehicle. She only brought it to the dealer to get fixed. (She's deceased now, so I can't ask her any questions.) I guess I'll have to run a new circuit. And then probably sell the thing, for it has 238000 miles on it. Thanks for the help.
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