2nd Gen Non-Engine/Transmission Engine speed sensor intermittant

[GAmes]

In post #1 of this thread https://www.turbodieselregister.com...ons/184945-electrical-woes-maybe-bad-pcm.html Dave M states



"I have a 97 and the truck runs but all of a sudden the Tachometer, Speedomotor, Odometer don't work. The generator is not charging and the MIL light won't come on with key on for light check. The fan works but AC doesn't. I believe it is controlled by the PCM also. "



I experienced the same failures today... ... ... sort of. When I first started the truck the check engine light flickered a couple times, then went off. When I first started out, the speedo wasn't working, and the tach would work intermittently. When the tach worked the alternator would charge. When the tach dropped to zero the voltage would drop, but the "gen" light did not illuminate. A couple miles later the speedo started working, but was all over the place, jumping as high as 50 when I was doing less than 30. The A/C, of course, was not working Only 103 outside. I drove across town, shut it off, completed my business and started home. Everything worked as designed. Has anyone who had an ESS failure have intermittant failures first? Do I replace the ESS? It is the original.



I hate intermittant electric problems!!! #@$%!

 

[CCiatteo]

I suffered most of those same issues and checked/cleaned the connection where the sensor harness plugs in (roughly up near the oil fill tube) and that proved to be fruitless. Then at the suggestion of others I cleaned and re-gapped the sensor down at the crank and that seemed to solve the problem. My issues arrived out of the blue for no reason and were entirely intermittent, just as you describe. Since the cleaning, things have been fine. When I was having the problem, it seemed to always coincide with wet weather, heavy rain and road spray etc. Never could confirm this though. I never experienced the alternator dropping completely out either, maybe because the ESS was generating enough of a signal to keep that from happening?



I'd try cleaning/regapping the sensor down at the dampner. If that doesn't work, then maybe its time for a new one. I checked the price at my local dealer (May of this year +/-) and they quoted me $180 plus tax, but it can be had from mopar online for about $125 plus shipping IIRC.



Good Luck

 

[GAmes]

Ya, the gap is the first thing I checked. I just replaced the front crank seal about 250 miles ago, everything is clean. Mopar4Less price is $140 shipped and I have one on the way. I'm trying to decide if I just go ahead and install it, or wait for a full failure. I'm on my way to PA next week, via south TX and Pueblo, CO so a roadside replacement could be a hot, unpleasant task.

 

[HHhuntitall]

..... I think you just told yourself what you want to do..... I'd have that baby fixed before I ever left Bell Co. if I were you! The CEL won't illuminate for a few minutes sometimes when the alternator quits... . the PCM thinks the engine is just off. I had one two years or so ago that ended up being an ignition switch problem... . it was shutting off the power to the PCM, I guess. I replaced the tach pickup, no help, and then tried the PCM with a used one, no luck. Finally tracked down no power unless you held your tongue just right and tweaked the key, hence the intermittent issue..... just a thought if your tach sensor doesn't fix your problem.....

 

[GAmes]

I had one two years or so ago that ended up being an ignition switch problem... . it was shutting off the power to the PCM, I guess. [/ch pickup, QUOTE]



I find that interesting. When I had the failure, which has not happened again, I jiggled the ignition key and that is when the speedo started jumping around. Since then I have driven it and wiggled the ignition and the key with no adverse reaction. Dang gremlins.

 

[HHhuntitall]

I find that interesting. When I had the failure, which has not happened again, I jiggled the ignition key and that is when the speedo started jumping around. Since then I have driven it and wiggled the ignition and the key with no adverse reaction. Dang gremlins.

Hmmm, well, sounds like you may have found it..... With as many miles as you have, it's bound to wear out at some point, unfortunately. As for gremlins, I always leave a few crackers and crumbs around, as well as a Sprite from time to time(no caffiene!!), and we have the understanding that if you don't chew on my wires, I don't burn the truck down with you in it!:-laf That and at the end of the day, they're so punch-drunk from riding with me, that they just want to lay around and sleep..... Kinda like my dog and kids... . never a problem sleeping at night after a day with Dad!

 

[GAmes]

Hmmm, well, sounds like you may have found it..... With as many miles as you have, it's bound to wear out at some point, unfortunately. As for gremlins, I always leave a few crackers and crumbs around, as well as a Sprite from time to time(no caffiene!!), and we have the understanding that if you don't chew on my wires, I don't burn the truck down with you in it!:-laf That and at the end of the day, they're so punch-drunk from riding with me, that they just want to lay around and sleep..... Kinda like my dog and kids... . never a problem sleeping at night after a day with Dad!

Down here, if there are crackers and crumbs in the cab there will soon be mice, so I'll pass on that. :-laf I made sure I have all the required tools to change the sensor and will just carry the new one with me until I get another failure. Judging by the failures I have read about I am past due for a sensor, but I hate speculating and throwing parts at an intermittant problem. However, I'm not going to buy a spare ignition switch for the possibility that is what has failed.