2012 Bluebird stop light problems (air brake)

This topic contains 2 replies and was last updated by mlee75 6 years 2 months ago
Author
mlee75
February 24th, 2015 10:37pm
Post
Hey All,

Working on a 2012 Bluebird bus with air brakes. The problem we are having and currently working on is that the stop lights work BUT........ with light pedal pressure (enough to turn stop lights on) the relay will de-activate after about 10 seconds. If you press the pedal on a little farther the lights will come back on and stay on all day if you wanted. We had a spare bus and we pulled the switches out of it after the first bit of testing led us to the switches, and we swapped these for the ones we thought were bad. Problem is exactly the same lights go on, stay on for about 10 seconds and the relay clicks off and lights go off, press harder and they come back on just fine.

Tomorrow we are going to do some more testing on the control side of the relay to try and verify if the body module is bad or if we are losing power at another place. From the wiring schematics the relay is grounded off the body and control is off the BCM. Power on pin 30 comes from the switches ( there are two on the inside of the firewall) and 87 goes out to the side panel and to the back. The draw from the rear lights is only 4.8 amps.



Will update tomorrow after we poke at it some more.

will-tilley
February 27th, 2015 6:58pm
That is an interesting problem you have there. I have had some issues with the body control modules, usually with the flashing lights or the wipers. I'm on my second BCM for wiper issues, just swapped one this past week . Can't help with the stop light problem as our newest air brake bluebird is a 2009. good luck
mlee75
March 2nd, 2015 12:00am
Here is an update on what we found, there were actually a few problems on this bus and each one had its own special little problem. First was the switches, yes the switches were bad on this bus as on a light brake press (just enough to turn brake lights on) they would come on for about 10 seconds and turn off. The switches operate at 2 - 5 psi and after checking all the line pressures and checking with known good switches there is just something wrong with the switch inside. Funny thing was we had a donor bus that we took switches out of for testing and they were bad too. On friday we had one of the drivers bring her bus down and used those switches and the "time out" problem was solved.



Problem # 2 was found in the left outside panel, there are a few connections in this panel that the brake light feed goes through on its way to the back of the bus. There was a connector with the pin style terminals that had poor terminal tension and when we were back probing the connectors we had temporarily corrected the connection in the pins. Went back through these at the end of the day on Friday and with lucky wiggle found and corrected this problem.



Problem #3 turned up late on Friday afternoon as well. While doing the wiggle test on the connectors in the side panel with the brake lights on we noticed the front park lamps were on. The switch on the dash was off but the front lamps were on, after doing some checks one of the guys went to the back of the bus and took the two bulbs out of the two inch brake/tail lights and presto the front lights went out. There was one bad bulb on the back closing a circuit through the brake filament into the park circuit.



Hope that all made sense and if there are any questions feel free to ask.

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