Fuse 23 Pops - No Blower, Reverse Lights, Shift Interlock !

1995 Contour LX 2.5 Auto

This one is killing me!

I pulled the leads from the revese lights, HVAC panel, and removed the shift lock selenoid and fuse 23 still blows!

I get 5 ohms resistance between the circuit and ground with all the connectors removed. I have wiggled the entire harness with no change in resistance.

No cracked, pinched, or melted wires.

What else is on this circuit that may be shorted?

By the driver side rear quarter panel (on the inside). There is a wire loom (harness) at the bottom. It could have been chaffed due the rear seat back being pushed up and down over the years.

A 5 ohm load shouldn't be blowing a 15A fuse. That's less than half an amp.

The list of loads on fuse F23 includes:

Gearshift interlock unit (if auto)
PNP swith (manual) or TR sensor (auto)
Air temperature actuator and the HVAC mode switch
Speed control module
DRL module (if equipped)
Multifunction switch

Check the circuit with the shift lever in reverse (power off) and see if the circuit now shows a dead short to ground. If so, then Tony's suggestion is likely correct in that the backup lamp circuit has grounded. Alternatively, you can just go to the backup lamp sockets and check from that end for a short-to-ground.

Speed control modules have also been known to short out....

Steve

I started with everything connected. The resistance was at 5 ohms and never deviated as I unplugged each connector.

I have not unplugged the speed control or the TR sensor.

I did notice in reverse (engine off) the meter went from 5 ohms to 9 ohms to ground.

I pulled the rear seat to wiggle the harness, but I did not remove the quater panel trim. I will do that tonight. That may be a good possibility - my wife drove the car on the day that this started (blowing one fuse after another) and had the kids with her. They sat in the back seat. I never have any passengers. We usually use my wife's car for family outings.

Sounds like the backup lamp circuit is the culprit, then.

Steve

Tonight I got 1.8 ohms to ground at the same test point as last night. :shrug:

It rained here today.

Tested the entire circuit with no change on the meter.

...that is until I unplugged the TR sensor. The meter immediately went to 398 k ohms! Several more tries confirmed the TR sensor to be the source of the short. Visual inspection found the connector to be corroded and green. I cleaned it with electrical cleaner and plugged it back in. The meter showed 12.4 ohms to ground - better. Started the car up and noticed as the car warmed up, the the resistance to ground rose as the heat dryed out the connector to about 200 k ohms.

The sensor is in pretty bad shape so I will replace it and see if the fuses keep popping after that point.

Thanks to projectSHO89 for pointing out all of the load areas for the circuit!