I just got back from a 14 hour roundtrip drive to Boise, Id from Portland,OR. I traded in my 2/month old 08 1500 QC Hemi for an 06 1500 Mega Cab 4x4 with 26,000 miles. First of all it was SO nice to drive home in truck that didn't shake the entire time. And it was really nice to be back behind the wheel of the 2500 platform which feels so much more stable and secure at speed. I'll post pics of the truck tomorrow, there was a bit more scuffs and chips on it than I would have liked, but it's a farm truck so no biggie. The window molding on both the rear doors needs to be fixed but before I take it in for warranty service I have a couple of questions:

At 67 mph and up to about 80 there is a whiring noise coming from the rear of the truck. I can't pinpoint exactly where, but the noise only occurs when I am on the gas.......perhaps exhaust related??

The other is the tachometer. Whenever I let off the gas the needle will drop about 500 rpms lower than the engine is actually running. Sometimes it will jump back to the right rpms and other times it will stay low. The majority of time once I step on the gas the needle will go back to the right reading. Any ideas on that one?

Other than those two items the truck seemed really solid and I am so much happier to be back in a HD based truck.

Thanks,
J

 

NICE. I can relate to your story. I had a 2004 2500 CTD which I traded in earlier this year. While I like the 5.9 HEMI, nothing compares to the CTD.

 

Gonna have to change your sig again Bldrman

 

Which engine did ya get?

 

Signature updated....no pics yet as I woke up to rain this morning. Anyone have some input on the two problems I listed?


Thanks!

 

That 2months owning that QC must have cost you a fortune!?

The only thing I could think of as far as the tach goes, how is the charging system? A sudden drop in rms would cause a spike for a milli second in charging and then drop like a rock. The tach guage is voltage related, so maybe there's a contaminated ground or your alt. or battery is weak?

The whirling noise I'm willing to bet is your pinion angle. Goin up hill your angle changes and when you hit the gas it changes again. I think that's something your gonna have to deal with! I'm just wondering if it will get amplified if you are towing going up a hill? Or towing period? if so, I would see if they can install new u-joints amd maybe that will solve the problem? Doubtful but wishful :-)

 

the hemi is 5.7 and the 5.9 is a magnum

 

Just a little info...

The tachometer gives an indication to the vehicle operator of the engine speed. This gauge is controlled by the instrument cluster circuit board based upon cluster programming and electronic messages received by the cluster from the Powertrain Control Module (PCM) on vehicles with a gasoline engine, or from the Engine Control Module (ECM) on vehicles equipped with a diesel engine over the Controller Area Network (CAN) data bus.

The tachometer is an air core magnetic unit that receives battery current on the instrument cluster electronic circuit board through the fused ignition switch output (run-start) circuit whenever the ignition switch is in the ON or START positions. The cluster is programmed to move the gauge needle back to the low end of the scale after the ignition switch is turned to the OFF position. The instrument cluster circuitry controls the gauge needle position and provides the following features:

Engine Speed Message - Each time the cluster receives an electronic engine speed message from the PCM or ECM it will calculate the correct engine speed reading and position the gauge needle at that relative speed position on the gauge scale. The cluster will receive a new message and reposition the gauge pointer accordingly about every 88 milliseconds. The gauge needle will continually be repositioned at the relative engine speed position on the gauge scale until the engine stops running, or until the ignition switch is turned to the OFF position, whichever occurs first.
Communication Error - If the cluster fails to receive a speed message, it will hold the gauge needle at the last indication for about three seconds, or until the ignition switch is turned to the OFF position, whichever occurs first. After three seconds, the gauge needle will return to the left end of the gauge scale.
Self Test - Each time the cluster is put through the self test, the tachometer needle will be swept to several calibration points on the gauge scale in a prescribed sequence in order to confirm the functionality of the gauge and the cluster control circuitry.
On vehicles with a gasoline engine, the PCM continually monitors the crankshaft position sensor to determine the engine speed. On vehicles with a diesel engine, the ECM continually monitors the engine speed sensor to determine the engine speed. The PCM or ECM then sends the proper engine speed messages to the instrument cluster, also known as the Cab Compartment Node (CCN). For further diagnosis of the tachometer or the instrument cluster circuitry that controls the gauge

Self test....

The instrument cluster actuator test will put the instrument cluster into its self-diagnostic mode. In this mode the instrument cluster can perform a self-diagnostic test that will confirm that the instrument cluster circuitry, the gauges, and the indicators are capable of operating as designed. During the actuator test the instrument cluster circuitry will position each of the gauge needles at various calibration points, illuminate all of the segments in the Vacuum Fluorescent Display (VFD) unit, and turn all of the indicators ON and OFF again.

Successful completion of the actuator test will confirm that the instrument cluster is operational. However, there may still be a problem with the CAN data bus, the Powertrain Control Module (PCM), the Engine Control Module (ECM), the Totally Integrated Power Module (TIPM), the Transmission Control Module (TCM), the Occupant Restraint Controller (ORC), the Controller Anti-lock Brake (CAB), the Sentry Key REmote Entry Module (SKREEM) (also known as the Wireless Control Module/WCM) or the hard wired inputs to one of these electronic control modules. Use a diagnostic scan tool to diagnose these components. Refer to the appropriate diagnostic information.

1. Begin the test with the ignition switch in the OFF position.
2. Depress the odometer/trip odometer switch button.
3. While still holding the odometer/trip odometer switch button depressed, turn the ignition switch to the ON position, but do not start the engine.
4. Release the odometer/trip odometer switch button.
5. The instrument cluster will simultaneously begin to illuminate all of the operational segments in the VFD unit and perform a bulb check of each operational LED indicator. The VFD segments and LED indicators remain illuminated as each gauge needle is swept to several calibration points and back. If a VFD segment or an LED indicator fails to illuminate, or if a gauge needle fails to sweep through the calibration points and back during this test, the instrument cluster must be replaced.
6. The actuator test is now completed. The instrument cluster will automatically exit the self-diagnostic mode and return to normal operation at the completion of the test. The actuator test will be aborted if the ignition switch is turned to the OFF position, or if a vehicle speed message indicating that the vehicle is moving is received from the PCM over the CAN data bus during the test.
7. Go back to Step #1 to repeat the test, if necessary.

 

06 Mega-Cab ,33x12x17's bone stock.

 

Actually I didn't lose too much....about $1,400. Definitely more than I would have like to but I couldn't take another day of the shaking, especially knowing that Dodge wasn't going to do anything about it.

I would have guessed the whirling noise was coming from the pinion angle too, but the noise occurs at any angle when I am over 67 mph and on the gas. It almost sounds like the feedback you get when a microphone is placed to close to the amp only not as loud. Also it is an interesting frequency as I can't hear it if I am facing forward, but if I turn my head to look at the back seat it is quite loud.

Parts/Service,
Thanks for the detailed write-up on the instrument cluster. I tried the self test and everything passed so I guess I have to leave it up to Dodge to diagnose......which will most likely lead to nowhere.....

Still raining out so I'll try and get some pictures tomorrow.