QuestionQUESTION: My 1990 Imperial (3.3 l) keeps blowing the #16 20 amp fuse, even when the car is not running, the doors are closed and the key is out. With the car running, I can get a 25 amp fuse briefly to power up the digital displays, etc., but then it blows too. The day this began happening, I had replaced leaky front air struts with coil struts. The, red, white, blue and black air strut sensor wires on each side are taped and not touching each other. I removed the compressor at the rear.
ANSWER: Hi Bob,
The fuse is the ignition off draw source which means all those devices that are needed even when the car isn't running. Included are:
electronic cluster (its memory)
body control module (the door lock system)
glove box lamp
radio electronics (memory)
door courtesy lamps
reading lamps
trunk lamp
vanity mirror
illuminated entry lamps
door key cylinder lamps
I don't see any involvement of this system with the air suspension wiring so unless by chance you shorted one of the pink wires that come out of fuse 16 to the IOD system while doing that work, this may just be a coincidence. What you will probably need to do is remove the bulbs/disconnect the devices in the IOD system, one at a time, and measure the resistance to ground from the cold side of the fuse 16 socket to see which one causes the resistance to rise from what it is currently...a near dead short. It could be a bulb/socket has become shorted. Do you recall any failures in these bulbs/devices before the fuse started to blow?
Roland
---------- FOLLOW-UP ----------
QUESTION: I found that by unplugging the plug (red with white stripe and larger black with red stripe) attached to the relay box under the hood that the fuse does not blow. The digital dash, etc does not work, though. The plug was oily inside and out so I thought that might be the problem. Even cleaned, though, the problem persists.
The electronic cluster is dead except for the seconds I can get it to power up on a 25 amp fuse. I guess I could try to remove it to check the resistance.
The door locks all work without fuse 16.
I have removed the glove box lamp, radio, door courtesy lamps, and reading lamps. I have not checked the resistance, but the fuse blows without them in. Do I still need to check the resistance if the problem persists without them installed?
I can remove the trunk lamp, vanity mirrors, and illuminated entry lamps and check the resistance.
I should be able to unplug the door key cylinder lamp and do the same.
No problem with any of these before. But the radio antenna would go partway up and down without the radio even on. It stayed up when the radio was on. I have unplugged all wires from the antenna.
ANSWER: Hi Bob,
I don't see a connection of the antenna to this fuse 16 problem. Until you have unplugged each of the items listed and verified which one is shorted to ground you will need to keep checking the resistance from the cold side of fuse 16 to ground. Of course you could keep blowing fuses as an alternative until you find it, but that is costly. It may be a wire from the fuse to one of the lamps/devices but I wouldn't get into that until you have exhausted simple disconnection. That would involve going through the splices that are involved in doing the distribution of the pink wire 'tree'. I wish there were a simpler approach but I don't know of it. So disconnect the remaining items doing the most accessible first. The body control module is located behind the kick panel on the passenger side, just in front of the door opening, near the floor. The pink wire comes to it on pin 16 of the black plug.
Roland
---------- FOLLOW-UP ----------
QUESTION: electronic cluster (its memory)
AnswerDo you mean that unplugging the cluster caused the reading to rise? If so, then that is your problem. You could look over the circuit board and see if you can find any electrolytic capacitors (small black cylinders) that show signs of leaking fluid onto the circuit board. Such a capacitor would likely be short to ground. Please let me know if this is what you find.
You could also look at the circuit board to see where the pink wire goes and trace those lines to see what they attach to.
