Escape Stalls When Turning on High Beams
Hello, had a good one in the shop today. Thought customer was crazy when the appointment was made. The vehicle stalls when the high beams are turned on. Sure enough when I got the vehicle in today, the vehicle will stall when you turn on the high beams. It will crank and not start until you turn off the high beams. Vehicle scan brought up numerous communication faults. I scanned vehicle with the high beams on and the PCM, RCM, and power steering control module do not communicate. Turn off high beams and those modules come back online. I haven't spent hours on this one yet but wanted to get some advice on where a good place to start could be. Anybody seen this before? Studying the wiring diagram and it looks to be a BCM issue. I will post findings tomorrow.
Thank you!
Sounds like a ground issue of some sort. High beams are pulling a ton of current and not leaving enough room for the starter to crank.
Likely, a power or ground is being overloaded due to an excessive voltage drop. I would start by monitoring voltage on related circuits, testing the most likely and easiest to access first. You can start at either end (source or load), just analyze and keep track of the results you get at each test point, and the meaning of said results. If the fault isn't outside of the BCM, it is…
Daniel Most have already pointed you in a direction that is probably the root cause, a high voltage drop at a ground. Before you spend a lot of time chasing the diagnosis to root cause, get with the customer to learn what they did or had done. My guess is something like a recent repair, possibly it was in the body shop, maybe a neighbor helped install headlights bought from the internet, maybe…
I would agree with everyone on checking the grounds first- but also Mark is right, look under the dash for any equipment / aftermarket / alarms / stereo system ect. that could have wired into the illumination circuit.
I would try unplugging the head lights first and see if it still does it.
Being an se I’m guessing you have a regular key and halogen bulbs. Low and high share the ground so I’m going the other way. Check voltage on fuse 74 with high beams on. On the same circuit is fuse 78 which either tells the BCM what position the ignition switch is or powers it. Burnt fuse, poor contact or anything else that lowers the current on the supply side circuit to fuse 74 because it also…
Had a similar problem a few years back with a mercury comet. Horn would blow with high beams on. Was my brother's friend's car. They came back to the house around 3 am. He got in his car to go home, hit the high beams and horn started blasting. Heard him drive all the way home. Took him a while to figure it out. Turns out I ran a jumper wire as a prank. I know this won't help you any but just…
Ok, sorry for the delay. This car was just purchased from a used car dealer and there was some quarreling about who was gonna pay the bill along with an aftermarket warranty company thrown in the mix. So we checked various grounds in the vehicle and found all good there. I noticed that one of the fault codes in the bcm said that a crash was detected. I reset the crash data and the problem went…