1994 4.0 coupe, USA spec.

When I press the brake pedal the voltmeter gauge drops a couple of volts and returns when I lift off the pedal.

I have heard of this on another forum. Suggestion was a bad/poor (white) multi-connector under the steering column with a large brown earth/ground wire. Cut off the connector and hard solder the wires together.

Anyone else had this problem, root caused it and cured it?

 

That happens on my 1994 4.0 CONV, I just assumed that since the electronics on the car are peculiar to start with, it was the drain with the brake lamps, never viewed that as an issue, everything works the way it's supposed to.


That's just me.............

 

I have the same issue with my '94 4.0. It is accompanied by a relay closing under the right bolster. I've suspected it is associated with the ABS system.

 

That happens to most all XJS's, I understand there is a fix. It involves rewiring the circuit by, by-passing the harness plug going into the steering column or the instrument cluster. not sure which but it has come up on other posts, I think Kirby's book may cover this.

 

My '94 is/was doing that Voltage drop with the brakes uuntil I replaced the brake lights with LED types. The voltage still drops but not as much. Now the turn signals really cycle fast because there isn't as much of a current draw for the flasher. I have the resistor pack to put on the turn signal but just don't have as much time lately to mess with it.
I did notice that the abs relay does cycle and cause the voltage drops also. I've seen some posts about the ABS system pressure vessel having leaks that may cause the ABS to cycle the pump to build pressure again. Another when I got time project.