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Monday, March 28, 2011

1997 F150, Dome Light And Chime Come On When Brake Pedal Is Pressed


I have a 1997 Ford F-150 4x2. It has a electrical problem I can not find. The small relay in the fuse box clicks (I think it is the second from the top), the dome light flashes along with the clicking relay, also when you hit the brake the dome light comes on real dim and the door chime beeps each time you hit the brake, it is as if you opened the door, regardless of the door being open or shut. And the power windows do not work. I am not real good at tracking down wiring problems, but I did a Google search and everything I found pointed towards the gem module. So I bought a used one from a salvage yard and installed it. It still does the exact same thing. How much would you charge to help me find my problem? I already blew $150.00 on a gem that didn't work. I would like to get this truck going again. 

Hi David,

Initially my though twas a weak body ground but it could also be a blown/missing fuse with a circuit back feeding (requires removing and looking at the fuse element to check it). Check your owners manual for fuse locations. You also could have weak body power supply.  There also could be wire damage at the brake pedal itself. Just a few things to check. Does the truck run?

I do not have a set fee for helping. I prefer for you to donate, as a percentage of the repair savings. Much like you would  tip a waiter, a percentage of the restaurant bill. 

Yes, the truck runs. was working fine, my sister borrowed it, brought it back and I got in it about 30 minutes later and it was a mess, I swore she must have done something, lol but couldnt think of anything she could of done. It had a aftermarket alarm in it, it was going off all lights were flashing, horn honking ect.. along with the other problems. I tore the dash apart and disconnected the aftermarket alarm, and that left me with what I described earlier. I am going to go to the shop now and check all of the grounds and power wires, along with the fuses. 

I checked the power and grounds under the hood, fixed a couple that looked bad below the ebrake. Checked the ground in the loom to the door. We have all data but I dont know how to read the schematics. 

Hi David,

Do you have a scan tool that will communicate with the GEM?  Have you checked the grounds behind the right and left kick panels? Is there any sign of a water leak around the fuse box or GEM? Although you replaced the GEM, there could be corrosion inside the fuse box. Let me know what kind of scan tool, voltmeter, test lights or other diagnostic tools that you may have access to.

We have a Tech 2, a Genisus, and a older snap on scan tools, and volt meter, test light, ect. I checked the grounds on the left kick panel, replaced the ends on a couple of them that looked bad. I didnt know there were grounds on the right kick panel. I will check there tomorrow if I get a chance. I work in a auto repair shop. But I do mainly mechanical work, engine and frame. My boss is good with electrical stuff but he is always to busy.

Hello, you were right, I found a rusty ground behind the passenger side kick panel. Thanks so much. Its great to have my truck back.

Hi David,

I am glad your truck is fixed.

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