89 300E Door Locks keep blowing fuse

[mpc]

Yesterday I got into the car and the temperature registered at 115 F. The car started fine and then I noticed that the dome light remained on, and the seatbelt light kept flashing. Both remained on the entire trip. When I tried to lock the doors, the locks did not work. I replaced the 16 A red fuse this AM, the doors worked once, then blew the fuse again. What did I fry? Thanks in advance for your help.

Matthew

[ejsharp]

Had you taken anthing on the car apart before this happened? Or did anything unusual occur such as rain getting into the car and soaking things?

[ejsharp]

Had you taken anthing on the car apart before this happened? Or did anything unusual occur such as rain getting into the car and soaking things? Little things can cause big problems.

I know of a mother who let her two little girls wash her car. One of them took off the gas cap and filled the tank with water from the hose. She had watched her mother do that numerous times at the gas station. Needless to say mom did not get too far down the road on her way to work the next morning.

[mpc]

Nothing else has been taken apart or tampered with prior to the fuse blowing. No water either. I thought that perhaps the extreme heat might have had an effect. I'll dig a little deeper this weekend. Thanks!

Matthew

[ejsharp]

Somebody might have some insight about the condition but it's not me. I would have to get out a wiring diagram and trace the circuit on the fuse you mention. Check the easiest and most suspect things along the circuit and then move to others if necessary. It sounds like a break or corrosion along parallel lines involving a short and cross current. I also suggest you subscribe to alldatadiy.com. There you can get on-line diagnostics for you car... including wiring diagrams.

[sbourg]

I doubt if the lines for the vacuum pump trigger signals at the door/trunk locks could be the source of the fuse blowing, but the pump itself likely is. It is located under the rear seat bottom, encased in foam. Unplug it and see if the fuse-blowing stops. If so, the pump itself is the culprit.

Note that if you have an air leak to one of the lock actuators, the pump will keep on running until it overheats and blows a fuse.

Steve

[ejsharp]

There is also another possibility if the pump proves to be OK. There is a crimp connection in the wires that feeds the vacume pump that runs under the carpet and pad located on the floor where the right rear passengers feet would rest. These wires corrode usually because water got into the car because the sun roof or windows were at one time or another left open during a rain storm. The water remains under the rubber pad and carpet and takes eons to evaporate thus corroding the wire connector located there.

To access the connector remove the carpet trim at the rear door and lift carpet and rubber pad. .. along with rear seat. But before you do all this make sure the fuse you are talking about controlls the vacume pump.