Ok, guys here we go... help a girl out

2002 Ram 1500 QuadCab 5.9L V8, 112k miles

I noticed this AM while sitting at a light that my truck will slightly rev itself. The Tach doesn't change, but the speedometer will jump to 30mph while sitting still. I can hear a faint click/tapping noise, but can't locate it & don't know if it's related. Got to my work parking lot, sat there in gear with my foot on the brake and watched - engine would rev & speedo would jump to 30, 50, and a few times it just went completely haywire and sailed over to 120.

Put it in park, no idle problems whatsoever - idles quiet and smooth, no rev jumps. Put back into gear, and revved in reverse, neutral, and drive. Then the alarm dinged at me and the emergency brake & ABS brake lights came on on the dash and stayed on.

Mechanic boggled at me over the phone and said he wasn't sure, hasn't seen anything like it - possibly a loose connection, and obviously something is interfering with the computer.

Since it just started this AM, my mechanic hasn't seen it yet (and won't be able to get to it til Monday, so here's hoping I can get thru the weekend) but I kinda want an idea of what I may be looking at - seems the general consensus is start with cleaning the crap out of the throttle body and look at sensors. No check engine light, and being a 2002 the key trick won't pull any codes on the trip.

Just wanted to see if anyone else has had something like this - thanks!

 

My truck is an 02 and the key trick works. Check the wire bundles leading to your PCM, see if any are worn and possibly arcing. The revving would lead me to think ignition system, but the speedometer involvement leads to the PCM.

 

You may want to check your battery for good connections. Also, have it tested to make sure your voltage is right as well as have them check out the alternator. It may not be putting out voltage at a constant rate. In older cars I've had, when the battery or alternator start going bad, weird things start to happen, i.e. lights coming on that shouldn't, speedometer needle jumps stuff like that. Start simple and work up from there is my opinion.

 

I had the same thing on my 03. It is the speed sensor on the rear wheel. Once you hit the gas the needle will go to your correct speed. I left it for 2 weeks becuase I couldn't get to my mechanic and was fine driving 300+ miles a week. It will start to do it when you are in park if you leave it for a while. My ABS light went on a couple times, all went away with a new sensor. ABS still worked though.

 

Thanks... my check engine light came on on the way home from work, so we'll see what a scanner says. I wish the key trick worked on mine, I tried it again this afternoon and I don't get anything on the odom :/

FM, you're the second person that's mentioned the speed sensor - mine's doing what you described, but did your speedo go crazy when your key was in the on position, but your truck wasn't running?

 

Pretty sure it did becuase when it first happened I was checking under the hood with the motor off, key in on position and you could hear the tic or zap that you hear evertime the needle jumps. When I mentioned the ABS light going on, that was only when hitting the brake and at almost a stop or sitting at a light for a while then it would go off when I started to move. I would have that sensor checked before looking at anything else.