merc question please

wrong group, but since your here it sounds like the diode pack is giving up on the alternator, it may still charge, but not at the full correct rate.

This is the wrong group to ask about a Grand Marquis? Last time I looked, the 1992 models were built by Ford. New ones are too, as a matter of fact.

Did the 1992 model still have the ole 5.0L or was it equipped with the 4.6L V8?

First, pop the hood and check the wiring harness that connects to the alternator. They tend to heat up and warp/melt and cause anywhere from a bad connection to a melted mess. (This may not apply to the 4.6L or the

Check the battery cables for corrosion, loose terminals/cables/crimps, etc. Check the starter solenoid while in that area as well.

If the light is still flickering, it could be the diodes going heat sensitive or just plain going flakey. You can rebuild the alternator yourself if you'd like, or just replace it. Most places will test the alternator for you, but being intermittent, it may test fine at the moment.

ok i got it wrong.we dont have the grand marquis in england and since the subject line said "merc" i htought this problem related to a mercedes, merc in the uk being short for..mercedes..obviously.

Check the Regulator, sounds like it could be going bad. Check the electrolyte in the battery too, especially if you have one of the new generation "Maintenance Free.." battery with a removable vent cap, that is over 2 years old.

Ahh, that makes sense.