Help! Brake lights stay on

[sayhey24]

I just had the brake position switch replaced at the dealer. Now my brake lights stay on while the car is turned on and the car will start without using the brake pedal. where do I or the dealer look next? Thanks for all the info on this forum.

 

[rexster314]

Take it back to dealer, it's more than likely their fault anyway.

 

[xlrlist01]

I just had the brake position switch replaced at the dealer. Now my brake lights stay on while the car is turned on and the car will start without using the brake pedal. where do I or the dealer look next? Thanks for all the info on this forum.

On replacing the brake pedal position sensor (BPSS), it has to be re-calibrated. This takes five mins with a Tech-2. It is almost trivial to do.

 

[sayhey24]

Thank you. The dealer had recalibrated the sensor. I brought the car back in and they traced the fault to a loose wire to the BCM. Tightened the connection and everything works well. The dealer spent over an hour on the car and charged me nothing for the time.

 

[xlrlist01]

Thank you. The dealer had recalibrated the sensor. I brought the car back in and they traced the fault to a loose wire to the BCM. Tightened the connection and everything works well. The dealer spent over an hour on the car and charged me nothing for the time.

Is there any possibility of getting more information out of the dealership? Tightening a connector is an unusual thing to do with modern harness ends, how did they go about it? I'm assuming it was the BPPS to BCM connector, which is BCM pin 31 connector 2, circuit 5380 (Tan) (in 2004), and/or one of the two references, pin 18 (5381) and pin 59 (5382).

 

[sayhey24]

brake lights stay on

Thank you for you insight. I will check with the dealer. During the time that the brake lights were on, the dealer Tech 2 could only read intermittently. It now reads every time...so far. Time will tell

 

[xlrlist01]

Thank you for you insight. I will check with the dealer. During the time that the brake lights were on, the dealer Tech 2 could only read intermittently. It now reads every time...so far. Time will tell

To anyone who hasn't seen these connector blocks/harness ends before, instead of being bolted together (and the BCM still has some of those 'old style' ones too), the design has a plastic catch that pushes forward over the end of the block which at the same time releases and separates the two sections. Inside, for each circuit the BCM has a small diameter pin which fits inside a corresponding metal sleeve in the harness end. These can be dismantled with a special pick. The connector sleeves are in pairs. There is a keeper which holds all the connector sleeves in, that removes easily. Then using the correct pick the tab holding each pair is gently squeezed open to the release point, allowing the sleeve to be withdrawn from the back of the harness end. The pick blade is about an inch long and under 1/16 inch in diameter. The sleeves are so small it isn't obvious to me how they can be tightened without risking serious damage to the BCM pin.

Maybe the dealer spliced in a replacement. Given they located and fixed the problem in an hour, that is pretty efficient. Maybe they had met this problem before.

I'm guessing that the Tech-2 was seeing an erratic reading, if so 'tightening' the connector would result in a steady reading.

What is perhaps more of a concern is the harness end design isn't supposed to have that sort of problem. It is widely used and is expected to be reliable.