Emergency hand brake light — how can I bypass the cluster?

toximus

toximus

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I need to bypass the cluster for my LS engine swap but would still like an indicator light for the handbrake and shuttle valve. I am trying to make all of my connections behind the dash for the cleanest wiring.

Do I understand that, when the hand brake is pulled, I should have continuity between ground and pin 9 of the C2 dash cluster?

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Confirming that's how it works.

Pin 9 of the C2 cluster connector should be treated as ground in the circuit.
 
Yes that is correct the park brake grounds that circuit when applied. It is run through the shuttle valve as a “prove out” so if the shuttle valve becomes disconnected you will not have a light come on when the park brake is pulled. The shuttle also grounds that circuit if a failure is indicated.
 
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It works like it's grounding the circuit. However, I think it actually uses the ground as a low input which the cluster uses to determine an output.
 
The brake warning switch is one of the hard wired lamps in the cluster. It works with no control from the cluster.
Turn signals and high beam are other examples of hard wired lamps.
 
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LONGJP2 said:
How did you determine this?
Click to expand...

My apologies. I was basing my answer on earlier models like mine that are just a simple lamp circuit.
Looking at your profile I now see you have 04 and 05 TJs. Checking the FSMs, I see brake warning lamps in later models are LEDs controlled by the cluster based on various inputs to the cluster.
 
Pure speculation here...but I wonder if Jeep was planning on adding door ajar indicator lights to the cluster? It seems that they operated the brake lamp as if it were a simple circuit on all of the years, and it seems like it would have needlessly taken extra wiring to have left and right doors separately pinned to the cluster?
 
In early models, where the courtesy lamps are directly wired to the door switches, the driver side door switch had a second wire for the cluster purely for the chime functions. The passenger door switch having no connection to the cluster.

In later models the extra wire isn't needed as both door switches have a separate input to the cluster. This is because the cluster operates the courtesy lamps. If the drivers door switch is detected, in addition to the courtesy lamps the chime functions if the key is in the ignition or lights left on.

Door ajar warnings could certainly have been added to the cluster, but I can't remember if my courtesy lamps go out when the first latch is engaged. If it does, it would mean the switches aren't sensitive enough to work unless the door isn't latched at all.
 
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