message center

[MRB73]

I recenty purchased another 92 Mark Vii SE after having one awhile ago.I had to put a new battery in it today and when i hooked the new battery up and turned the key on,my message center and overhead console did not come on.I checked the fuses and they are fine.Everything worked before hand so I am not sure what happened or what my next step is.Thanks for any help you can give me.

 

[Elessee]

I have an '88.. Chances are good that the electrical systems are similar if not identical wherever they match. Here's what my Electrical and Vacuum Troubleshooting Manual suggests:


Condition: No display at the Message Center with Ignition Switch in ACCY or RUN
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Possible Cause: No voltage at M/Center or MC is defective.
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ACTION:
Check Instrument Cluster is functioning properly. If it is, check fuses 16 and 6. If it is not, check fuse 17 or interior lamp.
(The message center, at least on my car, is served by those three fuses..)

Check connections in wiring circuits and and check circuitry for continuity

Remove connector C108 from MCenter.
(That's it's main connector... A big plug directly connected to it's rear)

Check for battery voltage at pin 9 (light green/pink wire) and pin 2 (light blue/pink) of connector C108.
(you should see near 12 volts on those pins)

Check for ground at pins 11 and 13 (black/white stripe wires)
(set the meter to ohms, connect the other lead to a good ground and read zero ohms)

If battery voltage is measured at pins 2 and 9, and ground at pins 11 and 13, replace the MCenter. [OR: "Repair the circuits as necessary".]
(In other words, if the thing is getting power and is properly grounded through the connector, the box itself has an internal problem.)
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I won't bother searching for overhead console diagnostics.. i think both devices share the same problem and fixing one will fix the other..

You say "I had to put a new battery in it today". Why? What happened?
If all you did is replace the battery with a new (?) one and that everything worked prior to that.. well.. Something doesn't add up. Try and remember if anything weird happened.. anything at all.
Is that ignition switch sloppy? Is anything else not functioning?

 

[MRB73]

Thanks for the information.I will be able to work on it this weekend.Everything worked fine before I changed the battery and everthing still works but the message center and the overhead console.The reason for changing the battery was it was turning over real slow a couple of cold mornings and when I checked the date code it was about 6yrs old so I figured before it gets real cold let me put a new battery in it.I went to Autozone and bought a Duralast gold for it.

 

[Elessee]

I suppose something might have shorted and a fuse was blown when the battery was swapped.

in order of my preferences..

I'd begin by double checking the fuses. The little owner's manual in the glove box should list which fuses power what accessories, as well as illustrate and number them.
Pull the fuses and make positively sure they are good.

Trace the battery cable lengths and see if they are in good shape.. no worn insulation.. no bare wire rubbing on some part of the wiring harnesses.

Since the car is new to you, use a good bright light and inspect the whole engine compartment and anything else.. like under the dash board.. for any wire-related oddities.. Follow all bundles of wire and look for loose connectors, or burned wires, bad smells, funky looking amateur repairs..or whatever.

If you can't find anything, do whatever it takes to remove that connector as outlined, (or just tap into the appropriate wires if possible) and see if power is reaching the message center. If it's not, you might have toasted a wire somewhere up stream, but the fuse didn't blow for some reason.

Otherwise the MCenter may be toast. Apply 12 V to it.. see if it lights up..