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Discussion Starter #1
Hey folks,

I'm new to the forum and have recently purchased a black '02 SEL. It's loaded and is a far nicer drive to work than my F150 (and cheaper for sure). The car has 108K on it and runs flawlessly. I put brake pads on the front but nothing else so far.

I have a red "parking brake" light that turns on occasionally. Today it was on for a total of 5-10 minutes then went off. It's not related to brake fluid as I've seen that mentioned here, I've checked and it's full.

Maybe 1 time out of 10 the traction control light will turn on and off a couple times when the brake light turns on. Usually the TC light goes back off but the brake light stays on for varying lengths of time.

It comes on while just cruising and without touching the brake or turning. I've seen references to parking brake switches but the TC light makes me tend to doubt that's the cause.

I'd welcome any ideas you have for stuff I can check.

Thanks.
 

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I don't mean to hijack your thread, but I am having the same problem with my '96 LX wagon. To wit: the brake light on the dash lights up after I brake and then use the accelerator. It lights for a second and then after a few minutes of driving, the light goes on and stays on until I turn off the motor.

Fluid is fine and I replaced the pads/rotors last year.

Consider this a bump! :dunno:
 

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the brake light might be a little tension in the parking brake line triggering it.. or possibly something to do with the abs
 

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The red brake lamp is not going to go on due to an ABS issue.

The only things that turn it on are the fluid level switch and the parking brake switch. Tension in the cable won't do it, the switch is a plunger type switch that is near the top of the pedal. Either one of the switches is going bad or it is a wiring issue.

When the one of those switches are closed, the GEM and the ABS module both recieve the signal. When the GEM sees the signal, it will turn the red brake warning lamp on. If the ABS module sees the signal, it is going to shut down all ABS operation (and traction control operation if equipped). This will turn on an ABS lamp or a traction control lamp.

I was having an issue with the brake warning lamp going one whenever I stopped and then immediately accellerated. The fluid level was near full but not at max. The fluid was sloshing forward then backward, tripping the light. Turns out now that I have a leak that got substantially worse.
 

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Discussion Starter #5
So what is the best way to check the fluid level switch? I've disconnected the parking brake switch and the light would still randomly come on and go off without any pattern.

I'm suspecting the brake fluid switch but am not sure the best way to test it.

I'd appreciate any info on testing this switch.

dj
 

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So what is the best way to check the fluid level switch? I've disconnected the parking brake switch and the light would still randomly come on and go off without any pattern.

I'm suspecting the brake fluid switch but am not sure the best way to test it.

I'd appreciate any info on testing this switch.

dj
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First thing to do if you don't have any diagnostic tools is to disconnect the brake fluid level switch and see if the light still comes on. You've already tried disconnecting the parking brake switch, so you know that the switch is not causing the problem.

Here is the wiring diagram:


Now, at this point, you have already disconnected the parking brake switch, and the problem still occured, so we can now eliminate that swtich:


Now, disconnect the level switch, and tell me what your results are.

If the light still stays on when you disconnect the switch, then we will have eliminated the switch, but if the light goes out when you disconnect the switch, then you know the problem is the switch.

That bulb labeled with the number 13 in the wiring diagram is the brake warning/parking brake lamp. It is turned on by the GEM. The parking brake switch and the fluid level switch do nothing but ground a circuit that is connected to the GEM. When the circuit is grounded, the GEM sees that signal and turns on the lamp. So, either the switch has to be stuck closed or shorted, or there is a short to ground somewhere in the wiring. All the GEM is doing is waiting to see the signal grounded out, it doesn't know the actual position of the switch.
 

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Discussion Starter #7
Well, here's what I've discovered. When the brake fluid sensor is disconnected the brake light doesn't come on. However I had noticed that when the brake indicator light had come on that the traction control switch didn't turn off.

Now, with the brake fluid sensor disconnected there are times when the traction control switch behaves in the same way just without the brake indicator. Then a quick flash of the traction control light and things are back to normal. This flash of the TC indicator would usually turn off the brake light when it was on.

So, it would appear to be a problem in the unit that manages the ABS/TC systems (at least that's my thought). What is the part called? Where is it located? I figured I'd pull a used one to swap it before spending money on a new one.

I'd certainly appreciate any help on this.

dj
 

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Discussion Starter #8
Anybody got anything to add? I'd love some guidance as to what the "GEM" part is and where it's located.

I've troubleshot as far as I can and would welcome any input. The traction control oddities make me think it's a control module more than a sensor but I've not had any experience with this system.
 

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GEM stands for Generic Electronic Module. It controls most of the body electical things. The GEM is located under the dash and is piggybacked onto the interior fuse panel. In newer cars, Ford refers to it as the Smart Junction Box.

The problem you are experiencing seems to be intermittant. So, you're going to have to do any troubleshooting only when the problem is taking place. A scan tool would be of huge help but you'd need something expensive to read codes and view PIDs from the ABS module and GEM. A scan tool would read what code is being thrown when the traction control light goes on and that would help point you in a good direction.

Going to Autozone or Advanced Auto parts to have codes read won't work. They don't use a scan tool capable of reading any codes except for powertrain codes.
 

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Anybody got anything to add? ......[/b]
Have you or anyone else with this problem found out what the cause is ?.

I have the identical problem also, and it looks like several others have had the same problem. I was hoping that someone may have diagnosed this, and it may be common to all.

I have eliminated the parking brake as the culprit. Though removeing the connector for the fluid level turns the light out, it is not the underlying cause. During the intermittent brake light coming on I never noticed my T/C light flashing. However, when the problem is there, the TC off light does not illuminate when the switch is turned off. So I believe that the T/C does not function when the problem is there.

I have not checked the wheel sensors yet. I suspect this could be a intermittent relay problem if there is one in the ABS - T/C circuit. Mine started very randomly and now occurs more frequenlty and for longer periods. I just turned 75,000 miles.
 

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Discussion Starter #11
We've definitely got identical issues (T/C flashing, "T/C off" turning off) so keep me posted if you hear of any solutions. I've heard some say the GEM module needs to be replaced but also requires programming which is a dealer thing.

I don't know if that's the answer since no one I've heard from has actually taken that step. I unplugged the fluid level sensor to keep the annoying brake light from coming on but that's not the long term solution.

Thanks for chiming in and keeping the thread active.
 
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