E38 trans fail safe and coolant heater question

**Bigcuba** · 08-13-2018, 10:07 PM

My experience with this started a few months before the car failed. I was having two different experiences that seemed to lead to the this. One was the car not wanting to start occasionally . The other displayed itself while driving. The car would suddenly jerk or pull back as if I slammed on the brakes for a split second. This seemed to increase from happening once a month to almost daily. Leading to the car one day starting but running in trans fail safe. Drove the car home and then it wouldn't start. The mechanic ended up changing the 30amp blown fuse/fuses and replaced the coolant temp sensor. Car drove ok for about a few days, then symptoms started again. Then broke down again.
Second time around, same mechanic found the fuse or fuses blown again and the thermostat heater was fried. So I did some research and saw to check connections at dme. Those looked great and had no damage from any moisture. Since getting the car back, I can tell the cause of the problem seems to still be there. About a week after getting the car back for the second time, its starting to display the same issues. Car abruptly hesitates and then it's fine. Car dies but starts right back up. I feel like I'm headed to the same problem and trying to figure this out.

Any advice?

Thanks in advance

**Mayorchuck** · 08-13-2018, 11:13 PM

Have you checked the wiring harness between the t-stat housing and the ebox? If one of those 30A fuses keeps blowing, you probably have some wet/deteriorated wires in the box that holds the harness. It's good there was no corrosion in the DME but if the t-stat MAP sensor was fried, you probably had coolant going up the loom causing issues. Could the the wire to the cam sensor are bare and touching on and off. Pop the lid off the wire box along the valve covers and take a look.

**Bigcuba** · 08-13-2018, 11:57 PM

Originally Posted by Mayorchuck

Have you checked the wiring harness between the t-stat housing and the ebox? If one of those 30A fuses keeps blowing, you probably have some wet/deteriorated wires in the box that holds the harness. It's good there was no corrosion in the DME but if the t-stat MAP sensor was fried, you probably had coolant going up the loom causing issues. Could the the wire to the cam sensor are bare and touching on and off. Pop the lid off the wire box along the valve covers and take a look.

Thank you for the advice. I'll take a look at those suggestions.