While towing my pipe trailer unloaded I shifted to drive and then after I got to 2300 or so let up and pushed the overdrive button to use overdrive . Did not work the light stayed on. Tried many times as I never had that happen. Same results. Drove for 10 miles and pulled off on a gravel road and hit a small pot hole the ac stopped blowing cold . I though this not happening . Stopped the truck and after looking in the fuse box the ac when to working as I heard the compressor kick in. ok must be a bad connection bad ground or what ever. After taking care of some work that I had went to that location I headed home . After driving for 20 miles the overdrive light on the button went out after I pushed it. The cruse control worked . The ac never stopped working . Never have had a electrical problem ever on the truck since I bought it in 98 . First time for everything I guess. I have a couple of ideas , brake switch , bad grounds and battery cables not sure but will check , any one ever had this happen to them or ideas thanks for advice Jim

 

First I appreciate every one that has read the thread , not sure what is the problem is yet , ordered a new crank sensor . Will try that , I really don't like part changing but I am tired of this problem . Am not going to take the truck to a dealer to parts change . The tack flickers the alternator seems un stable and even seems to wont to be overcharging , water in fuel lamp flickers ac wants to come on and stops clutch in and out. All of these things seem to indicate crank sensor . I hope that's it Jim

 

If your tach is working, it cannot be the engine speed sensor.......
This is probably going to be one of those trace the circuit, find the common joint and figure out what is wrong deals.

I re-read it, you say tach is flickering, I would first locate the ESS connector towards the top of the engine, take it apart and spray with contact cleaner, sometimes, especially with an engine that leaks oil, it can get oil in there and cause an intermittent no tach, which kills everything else you describe.

Do you have a factory service manual?

 

Your right about the sensor . It did not make sense to me ether but a friend of mine thought so. I know it is a simple problem but so far which I have not spent a lot of time trouble shooting is a real pain in the but. Now the alternator seems to wont to control steady at times it goes to the up a bit 15 or higher volts and the tack wont to start not being stable . I understand what the overdrive button does but how does it get the power to light bulb. There are times when I push the button nothing and other it wont light up to indicate its working . Thanks for any advice Jim

 

What year truck are we talking about, 1998?

 

It a 95 ' Could not use the truck this weekend so I had to use the trailer blazer . Not a big deal only a small trailer to tow. We are trying to move . At any rate when we got home and unloaded I started up the truck everything worked good . The overdrive lockout button worked as it should light up when pushed and go out on the next push. The alternator charged steady 14 volts ac good . Ran for a few minuets and then the alternator started to climb to say 15.5 or more . Killed the engine restarted the alternator running higher now the overdrive button will not light up on a push . Acts like maybe the computer is opening up to protect it self not sure Jim

 

Took the day of from work to mow and it rained lol . Started the truck and every thing is normal for now . I think the ecu cooled down . I believe there is a wire shorted or high load on the circuits. I am going to try to buy a manual to trouble shoot the circuits hopefully to fix this pain in the but lol . I wont to thank everyone who has suggested thinks . I have read many of Infidell posts on the matter real smart guy Jim

 

My cruise control worked intermittently on my old 96 cummins,
Took off all battery connections, cleaned everything, replaced ends on all small wires going to each battery, replaced ends on main power wire/grounds if needed.

That fixed my intermittent cruise control 100%.
It was great getting cruise control back lol

Might not be your problem but its worth a try if you have any corrosion around your battery terminals or wires

 

I cleaned the battery's cables and the grounds all I could find when this started happening Yesterday when I got home I started the truck and it is normal everything working lol thanks for the suggestion I appreciate it Jim

 

The light on my OD button will sometimes come on and the tranny will shift out of OD. I have always been able to push the button and have it work. Perhaps I should worry about future issues? I will check the stuff the others have posted here.

Cheers, Gus W.

 

I finally ordered a service manual and checked for codes . The truck started overcharging on alternator , or sometimes not, tack would drop out , loose the light for overdrive lockout. loose overdrive, cruse control, ac , . Kill the engine let the truck sit for a while cool off and every thing is good . I went threw this a few times and did not know of any circuits that would do that except the cpm . Ordered a rebuilt cpm from a online dodge dealer at a decent price . There was only one in the USA in the dodge system . Not much demand for sure . Installed the pcm drove the truck for an hour last night no problems all good .

 

Drove the truck for a 100 plus miles and go some hay for the horses . No problems with ac not one time or tack , Alternator dead stead . Gone is the water in fuel flashing off and on, Loosing power to the lockout lamp . I hit one bump in the road and a very noticeable one lol . The cruse dropped out and I though what the heck . Sort of . After I had time to think I realized I had two problems, the brake switch is doing that . Sure enough if I just pushed it sideways a bit or even moved it a mil it dropped out and probably overdrive and lockup. Push up on the peddle and not a problem . Will fix that tomorrow . There is the problems and how I got them resolved . Thanks for all your help and suggestions Jim