g741.org

Just thought I'd pass this along in case it helps others.

The brake pressure switch in our truck failed after 5mo/1000mi. Unfortunately I don't know the make of the switch because it came with the truck, it was new and unmarked. The failure mode was the switche's terminals shorting to the housing/ground. This caused the circuit breaker to trip when any position of the light switch was used. I'm thankful for the breaker because I heard it cycling and this alerted me to the problem. I have a new switch on order. This is the second brake pressure switch I've replaced recently on my vehicles and they are pretty generic parts with what seems to be suspect quality! I'm sure happy the circuit breaker worked well and my lack of brake lights didn't become an issue!!!

Andy

I would look for NOS. all the Chinese junk parts fail. I bet that is where the switch was made. the last 7 parts I bought for my daily driver have all failed. I have resorted to the dealer and ebay/CL for good used or NOS

Sad, but probably true... I went through an ignition module saga a few years back that took no less than 7 attempts to get a part that did not have an intermittent failure. It's good fun when spark is cut randomly, especially on one of our local bridges. At least it's quick to diagnose .

Andy,

An NOS brake switch is becoming a pretty rare bird these days and they run about $95 each. It was unique to the M38 and the M37 (because of the Douglas connector)..........but I can show you a dirty little trick that can save you a ton of money. Don't throw away your old switch and shoot me a PM or email.

regards,
bob

Bob,
The switch on the truck was not original. It was one of the generic ones with two male bullet style terminals. I made a pigtail to connect it to the harness when we redid it so I didn't butcher the Douglas connectors. We'll see how the replacement from NAPA works...

What's your trick with the Douglas style switches, I'm curious.

Andy