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I passed a semi on a 2lane earlier.....well,he flashed his lights so I got back over....to thank him I hit my 4way's.....when I did my RPM's jumped up by about 300???????turn the 4ways off,about a second later RPM's went back to normal.Thought it was a fluke...but tried it a few other times and same thing....so....WTF?????no jump in speed or anything...kinda like the trans is slipping.This was at a steady speed(65mph),not increasing.
this happen to anyone else?(if not...I wish I had a dollar for everyone that does try it on there way home from work)
I think your torque converter is locking/unlocking. It's tied into the stop light system. You may have a stop light burned out, look at the third brake light, on the cab, too.
You have a malfunction in the multi-function switch or a burned out third brake light bulb if the TC is unlocking.
When the hazards activate, the multi-function switch disconnects the brake light line from the tail lights. The third brake light isn't supposed to light with the flashers.
If the third brake light bulb is burned out, there is no longer a ground on the brake light switch and the PCM will unlock the TC. Note that it will also cancel the cruse control and if you're towing a trailer, the trailer brakes will activate with the hazards on.
thank God someone figured this out! mines been dong it for like ever. i replaced the multi-switch and everything. and yes, i do have a burned out third brake light. i been too forgetfull to replace it. i posted awhle back about this.
wow.... how the hell did you guys figure this one out? lol
Yea I agree with this. mines been doing this also.. But i replaced all the lights up there last weekend just because.. haven't even tested it out yet.. Thanks guys never would have thought about this.. freaked me out on the way to Dallas towing a car a couple of weeks ago.. cruise kicked off and the damn truck surged exactly as he said. nobody I ask knew why.
I know that if I'm toying the toy hauler, bad things happen if I turn on my hazzard lights, it pops a fuse and locks the tranny up to where I can't shift out of park, and the ABS light comes on, but change the fuse, and no hazzards with the trailer hooked up and I'm good.