2nd Gen Non-Engine/Transmission Tach dropping out/CELs popping on???

[CCiatteo]

On the way to work this morning my truck developed an electrical problem. Out of nowhere the Tach started to drop out/flutter and simultaneously the CEL, GEN light and "Wait to start" and "Water in Fuel" will come on. No interruption of power to the engine, fuel solenoid stay open. Radio wasn't effected. Best I could tell the dash lights didn't seem to dim (headlights were on at the time. ) No fuses popped in the cab or in the engine compartment. On the way home from work, the same problem. It seems to occur going over rough patches in the road. I can also duplicate the problem if I rock the truck vigorously side to side, with it running and the parking brake set.

Just now I checked the obvious (to me anyway) stuff:

*Batteries are secure, connections are clean and tight.
*All fuses are in good.
*Alternator isn't making any crazy noises.
*Volt gauge isn't showing anything out of the norm, its rock steady.

No parts or electrical gadgets have been added or swapped in the recent past.

Where do I start to look?

One thing to keep in mind, I live in central NJ and over the last 12 days we've had significant rain just about everyday, so I'm not sure if the excessive moisture has gotten into some place it isn't really supposed too?

Any advice or things to check is welcomed. The truck starts, idles, runs fine. I just don't want to burn to the ground because of a bad wire or connection.

I have a video i took with my cell phone

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Thanks

 

[CCiatteo]

I did some searching and more screwing around and I am almost 100% it is my Engine Speed Sensor (Crank Position Sensor?). I'm gonna swing by my local dealership and pick one up. It seems to be the only thing that could cause all those things to happen at the same time.

I pulled apart the connection at the top of the engine near the oil fill tube and it looked clean, no broken/abraided wires. I gave it a shot of contact cleaner anyway, but no changes. The problem still occurs.

Oh well. I am all ears if there any suggestions out there?

 

[snappy]

Check the electrical connection for the engine speed sensor aka crankshaft sensor. It is located just above the harmonic balancer.

 

[Mhannink]

i had that happen from time to time for a while then i adjusted the sensor and it went away

 

[DanielClosser]

When this happened to me, I found corrosion on the battery negative post. Cleaned and problem went away.

 

[CCiatteo]

i had that happen from time to time for a while then i adjusted the sensor and it went away

When this happened to me, I found corrosion on the battery negative post. Cleaned and problem went away.

I'm gonna have a closer look today. I priced a new sensor from local dealer and they want $175. On line I can get it for about $135 to my door. Either way I'm going to exhaust all options first because the problem is intermittent. It was fine for 2 days, then yesterday acted up again.



Corrosion or a bad ground or maybe it slipped out of adjustment all seem very possible at this point.



Truck runs fine, though with no issues. I wonder what that sensor is actually doing for my truck. Being a 5spd, it doesn't have anything to do with the transmission. Speedo is mechanical? Mechanical injection, so no inputs there?



I'll post up what I find.

 

[ewcmr2]

Speedo is electrical. Speed pickup is in transmission tail housing (2wd) or tranfer case (4x4)

 

[PatrickHansen]

Check your camshaft position sensor.

 

[Mhannink]

that sensor is mostly for the tach on the dash the computer looks at it too but it cant control anything so its also just looking. the only thing it affects is the cruise control.

 

[CCiatteo]

Check your camshaft position sensor.

Does my truck even have a camshaft position sensor? If so where might it be located?



Chris

 

[snappy]

I have never found a camshaft position sensor on a 12 valve. To the best of my knowledge, there isn't one.

 

[HD-J78]

Have you checked Geno's Garage? What about a local Cummins dealer? I just replaced the cam and crank sensors on my 2000 24V and got both from the local Cummins dealer. His price was slightly higher than Geno's but after shipping it probably would have been more expensive. Of course I have the disadvantage of living in AK, which really isn't a a disadvantage in my opinion

 

[HHhuntitall]

Check they spacing between your crank sensor and the harmonic dampener. If there is too much of a gap, the sensor may be losing contact. This can happen when the magnet gets weak, moisture gets into the sensor, or it just wears out. This happened on my own '97, my '93, and several other trucks I've worked on. The computer uses the signal from this sensor to run the tach, but also uses it to trigger the alternator function. Without a signal your alternator will not charge, your A/C will not cool, as the compressor will not engage, and it triggers the CEL to tell you there is oil pressure, but no engine speed reading or alternator function, and to check for a problem. Engaging the sensor closer to the dampener may help, and if there is a lot of oil and dirt buildup, cleaning that off will help, as well. And it just may be time for a sensor, but try adjusting it first, if there's a considerable gap. I'd say try around . 020-. 040 gap, I can't remember what the book says.