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sprinkles08, ASE Certified Technician
Category: Jeep
Satisfied Customers: 23001
Experience:  Chrysler/Dodge/Jeep Master Certified, ASE Master and Advanced Certified, Trans and Hybrid Specialist
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Grand Cherokee Ltd: Iam getting a "Service Elec Brake System"

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Iam getting a "Service Elec Brake System" error with an "ESP" Icon, but only when I turn on the parking/headlights on and drive it awhile. Got codes read and had a B107C come up.
Hello and welcome to JustAnswer!

The code is actually C107C, correct? B107C isn't a valid code but C107C would be related to the symptoms you are having.

C107C sets when there is a mismatch between the two switches in the brake switch. There are multiple sets of contacts in the switch and they are looked at to make sure they agree, this code sets when one switch is open or closed and the other isn't.

Outside of the switch itself possible causes for this are wiring, connections, the front control module (FCM), and the ABS module.

Take a good look at the brake switch connector terminals and wiring in the vicinity of the brake switch.

If nothing can be seen then the next step would be to use a scan tool to see which of the switch signals is causing the problem and what it's doing, which state it's stuck in. From there the wiring can be tested accordingly.
Customer: replied 4 years ago.

Where are my Front Control Module (FCM) and ABS Module located? ('05 Jeep GC Ltd 4.7)

The FCM is mounted to the fuse box under the hood.


The ABS module is mounted to the ABS hydraulic control unit under the hood. If you find the large aluminum block where the brake lines all go in you will also see a large electrical connector, this is the module connector.

Customer: replied 4 years ago.

Any idea why this would happen only while the lights are on?

That may be a coincidence or it could be a wiring or module issue. The FCM is what controls all lighting so if it's truly related to lights then the FCM could be the cause.
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