Voltage spike when braking

T

TAA1971

New Member
Joined
Aug 23, 2024
Messages
3
Location
Wisconsin
2012 Rubicon. Getting C2101, C2103 & C102B when braking hard. The battery, ABS & traction control light come on, but can be reset when turning off/on. Changed the wheel speed sensor and connector (I broke the connector). I can see the voltage spike to around 16 volts on a graphing scanner when I brake hard, but goes back to normal immediately (just a spike). Someone has added a lot of extra lights. I disconnected those, to no avail. The TIPM and alternator have been replaced. I added ground wires, frame, engine, body. Also, get the same issue when I pulled all the fuses related to the ABS and shut off the ABS temporarily with a JScan. The wheel bearing feels good. I've read all the other threads and am completely stumped. TIA!
 
Last edited:
TAA1971 said:
not specifically, but it doesn't happen in reverse or just parked. I would think if it was a brake switch, it wouldn't matter if I was moving or not. Correct?
Click to expand...

It makes sense to me. To rule out, have you braked hard in park and reverse though?
 
  • Like
Reactions: BLACKJKU
Did you ever figure this out? My customer is also experiencing this phenomenon with every checked, there is a spike in voltage only when braking hard in a straightaway. with the computer snap on connected I have a voltage spike 25.5volts, alternator, battery connections, fuses, grounds all checked and in working order. even the battery is now changed and still get it from time to time. Would love to hear what the solution to this was.
 
Did someone install aftermarket LED bulbs? Hard to imagine where you're getting the increased potential/voltage from during a brake event, though it's possible that some of the LEDs are acting as a capacitor of sorts and are back feeding during their voltage decay.
 
Top Bottom