okay, i have been driving the bomber i bought, daily, since my rig took a poopie, and filled the crankcase full of fuel via the front seal of the I.P.

anyways, ever since i brought the bomber home, it has had an intermittent speedo/cruise/O.D. issue. its wierd, everything will be working fine, i will be cruising on the freeway at 65mph, and donk, all 3 will go away. then after a random amount of time/distance (sometimes 100ft., sometimes a whole day!) they will just come back. all three at once. never loose just one, its always all three. here is what i have done so far: wiggled the VSS wires/plug, ALOT, because it seemed to work! LOL. well the other day it went away and dindt come back, so i replaced the VSS, and plug. and all was good for 2 days. i thought that solved the issue. then today i lost them again twice! dang-it! didnt bother to wiggle the plug/wires because they are new. they did come back fairly quick today. i have gone over the harness, and looked for chaffed/shorted wires, but didnt find anything (i know that doesnt mean its not the problem! hard to see everything as this truck is filthy) but i am left thinking (and i dont know this for sure because i really dont know how the systems works) that it almost has to be the computer??? is there anything else that will affect all three functions at the same time? every time. intermittently like this? the truck in question is a 93' D350, with a 518.

 

It seems the first thing is checked is the grounds. They seem to be a real problem for Dodge. After that you might check your crank sensor for clearance. Also check its wiring up the front of the engine. Check your throttle position sensor although I don't know if that would stop the speedometer from working. WD40 is your friend. Follow your wires anywhere there is a plug unplug it spray it with WD-40 then plug and unplug it a couple of times. Good luck, Mike.

 

When mine was doing it I found that some of the insulation on the wires was worn through. The wrap on the outside looked fine but had dirt in the wrap and over time of rubbing it had worn through the insulation. I taped up the worn section and that has fixed it for the most part. On a few rare occasions I still have the issue.

 

thanks guys! i do believe it is the wiring. yesterday when leaving work it was "out". i pulled over, popped the hood, and gave all the wires and plugs at the back of the head where everything comes together a good wiggle-jiggle. got in and drove away, and everything was working.

 

smack the dash!

 

same as yesterday! left the house this morning to make a 120mile parts run (southwest diesel, Lopers, and rocky mountain cummins) and speedo, O/D, and cruise were N/A. went down the road 3 miles. pulled into gas station, popped the hood, wiggle-jiggle wires at back of head, and drove away with everything working. at least its consistent! LOL