Hey All -

So I replaced my brake booster as I was having two codes related to lean. After completing the brake booster install, and turning the key on...I noticed the brake lights were lit up but my foot was not on the pedal. In addition, I can change from Park to any gear without my foot on the brake.

The vehicle appears to think the brake pedal is depressed but its not. I reconnected everything as it was....any ideas?

Thanks

 

The most likely culprit is the brake light switch. Is the brake pedal rising to the previous height? The brake light and cruise control switches are activated when the pedal moves away from the switch. Make sure the switches are contacting the pedal.

 

The pedal is not rising to previous height - the switches were working fine prior to the booster being replaced.

--Update I resolved the problem...for anyone else, disconnect the brake switch, twist and remove it from vehicle. Firmly pull out the black plastic plunger (you'll hear some clicking) - reinstall switch...press brake pedal a few times and voila....resolved.

So one last question, what is the other switch thats green higher up cruise cancellation?

Thanks

 

Yes that is the cruise cancel

 

Hey there Mark, where did you get the new brake booster from? I think mine is done. I've had the P1071 and P1074 come on every drive cycle for months now, but they go away after a few minutes. What's really happening is the car goes into limp mode for a few minutes every drive cycle, but then returns to normal operation after those few mins. Pep Boys said the brake booster has an internal leak. Parts and labor is $600.00 to R/R.

I watched a YouTube vid on how the brake pedal should behave when the car is running vs not running and the Jag failed every test

I happen to be up on my X Type vacuum leaks. I've been thru the vacuum hose threads here regarding the connections that are easy to reach and replace on top of the engine. I've replaced most of that. The IMT gaskets are 6 years old, but I doubt that's a culprit.

Here is the test I found:

Test 1: With engine off, pump the brake pedal 4 times and hold. Start the car and the brake pedal should sink. If it does brake booster is good.

Test 2: Start car and let idle for 2 minutes. Press and hold brake pedal. Turn off the engine. Pedal shouldn’t rise for 30 seconds. If it rises you have a problem with brake booster.

Test 3: Start car and let idle for 2 minutes. Turn off the engine. Pump brake pedal 3 times. The pedal should rise a little bit higher after releasing each time.

 

A far fetched idea is that there is simply air in the lines. I did have new rotors and pads installed at PepBoys 4 months ago. After the service the brakes were squishy and had low braking power. I thought maybe they left air in the lines.

I've let them burn in for a while now and they suck. I only have real braking power towards the bottom of the pedal travel. ...a new booster sounds good, here comes the quintessential question; What else can be addressed at this time? Master cylinder? I imagine so