Bizzare Insturment behavior

[DBazley]

Hello, I'm new here and am glad I joined up. Got the TDR a couple of years ago, now I'm back. Nothing like an unsolvable problem to help you renew the lapsed subscription ! I've had my 1997 2500 Ram for 120,000 miles and hope to help give feedback to others.



As I'm new to the site, can anyone suggest how I might locate any prior discussions on Insturment / electrical anomolies or charging system glitches?



They cropped up all the sudden, I first thought they were related to the Water-in-Fuel sensor wires that broke, but I repaired them, and the problem remains.



Quick description: Tachometer swings wildly, check engine light / generator light flashes intermittently, cruise control inoperable, and now charging ammeter shows low voltage & charging to 10 volts. Quite a mix of problems.



I've checked the fuses, all seem to be ok. I am stumped !!

 

[Shooter]

I think all of thoes funtions are handled by the PCM on the 24v, not sure of the 12v.

It could be a loose harness connector, harness that has rubbed through and shorting out, bad ground some where.

All of the wonderful things that really take some time to track down.

Good luck

 

[DBazley]

What exactly is that PCM?

Shooter, thanks for telling me what I didn't want to hear. Naw, it's a place to start, but hey what exactly is a PCM and where do I look for it ?



I absolutely abhoor electrical problems cause they're so darn elusive. I think I'd rather go to an IRS audit or have a root canal without novacane!



But I thank you and hope others can add more input as well.



Wishing you no similar troubles, David

 

[Bob Wagner]

i would search the archives

I believe this is the correct procedure.



if you push down and hold the trip odometer button and then turn the key to the start position and wait for the chec ...

word to appear in the trip od position it will run a check of all gauges.



like i said i've done it b4 but not sure if the sequence is right



edit yep just tried it out

 

[DBazley]

Bob, on what year truck?

Bob thanks for the idea. Is this true of all year trucks? Mine is a 1997 with the mechanical odometer, not the digital. I don't know if it matters, perhaps?

 

[Missouri Mule]

DBazley ,



Forget the PCM go directly to front of engine look down at vibration dampner. You will see a sensor (in the diesel application it is known as the Engine Speed Sensor in gas engines and 24 valves crank speed sensor) hoovering over it, if it looks like it is the right position follow the wires up to the connector. The connector is behind the wiring harness and twelve o'clock high of the sensor.



This connector is known to get dirty or bent/burnt pins which will cause a lot problems because the engine speed sensor sends data to the PCM and other electrinonic components so it can operate many things.

Engine speed sensor directly or indirectly involved; tach, alternator, (it turns on the ASD; Automatic shut down relay which sends line voltage to the EVR in PCM which tells the alternator to put out current).

TPS= shifting for Auto trans, and cruise.





BTW while you are up in that area check the ground bolt next to TPS if you have 5 spd just look near front of intake manifold (top). AS I recall the PCM ground is located there with a few others.



On alternator if the asd relay or the battery temp sensor is not working the alternator will not recieve message to put out current and charge light will come on.

 

[Howard Durand]

If you have a dc voltmeter, check your voltages at the Power Distribution Center to see if your voltage is fluctuating.

Before digging too deep into the system, make sure all of your battery connections are clean and tight and both battery grounds are good.

Make sure all connections at the Power Distribution Center are clean and tight. Check every ground connection you can find.

Once these are all verified, then start looking for individual components that might be the problem.

Do you have a manual? If not, get one!!!

If you don't want to spend the money for a Dodge manual, Haynes puts out one that has good wiring diagrams.

Good Luck!



Load test the batteries too.

 

[DBazley]

Will check all this out & Report back

Gentlemen:



Thanks for the suggestions, I think now I've got some detective work to do, and once I've searched out the things you've mentioned, I'll report back on the results.



Just tell me where to send you the payment, once it works!



David aka DBazley