every now and then when I start the car the speedo needle sweeps like mad and then stops lower than the 0 and stays there so I have no speedo .. any ideas what causes this ?

 

Usually a useless battery, a battery so weak that it draws everything to start the car and the needle bounces the wrong side of the pin.

Can I assume it somehow - self repairs ? - if it happens """every now and then when I start the car""". No idea if holding the trip-button trick works on your model.

 

just the speedo or does the rev counter do it at the same time?

Regards

Richard

 

just the speedo all other dials are ok

 

If it's just the speedo doing it, then it's not the battery problem.

Options are the speed sensor in the gearbox, gearbox ECU or instrument cluster. You'll need the fault codes read and a bit of diagnosis to track it down.

Whereabouts are you?

Regards
Richard

 

I've read of this wacked speedo problem many times on many forums. Didn't see the OP post anything about erratic shifting so that eliminates the speed sensor and TCM (ECU). A single signal goes to the speedo and the TCM. I have read of a weak battery effecting just the speedo. Most of the time the instrument cluster calibration test posted below will fix it. That or removing the instrument cluster and manually flopping the speedo needle back to where it should be.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

DIAGNOSIS AND TESTING - SELF-DIAGNOSTICS
The instrument clusters are equipped with a self diagnostic test feature to help identify electronic problems. Prior to any test, perform the Self-Diagnostic Test. The self diagnostic system displays instrument cluster stored fault codes in the odometer display, sweeps the gauges to the calibration points, and bulb checks the warning indicators. When the key is in the ON position with the engine not running, the MIL will remain illuminated for regulatory purposes.

To activate the Self-Diagnostic program:
With the ignition switch in the OFF position, depress the TRIP ODOMETER RESET button.
Continue to hold the TRIP ODOMETER RESET button until Sof and a number (software version number (i.e. Sof 3.2) appears in the odometer window then release the button. If a fault code is present, the cluster will display it in the odometer display. When all fault codes have been displayed, the cluster will display “end” in the odometer display. Refer to the INSTRUMENT CLUSTER DTC'S table to determine what each trouble code means. INSTRUMENT CLUSTER DTC'S DTC DESCRIPTION
100.0 LOOP-BACK FAILURE
100.1 ABS COMMUNICATION FAULT
100.2 BCM COMMUNICATION FAULT
100.3 EATX COMMUNICATION FAULT
100.4 FCM COMMUNICATION FAULT
100.5 ORC COMMUNICATION FAULT
100.6 SBEC/DEC/MCM COMMUNICATION FAULT
200.0 AIRBAG LED SHORT
200.1 AIRBAG LED OPEN
200.2 ABS LED SHORT
200.3 ABS LED OPEN
200.6 EL INVERTER TIME-OUT
200.7 EATX MISMATCH
400.0 EEPROM READ/WRITE FAILURE
400.1 IMPROPER POWER DOWN DETECTED


CALIBRATION TEST
The CLUSTER CALIBRATION table contains the proper calibration points for each gauge. If the gauge pointers are not calibrated, a problem exists in the cluster. If any gauge is out of calibration, replace the cluster.

CLUSTER CALIBRATION SPEEDOMETER CALIBRATION POINT
1 0 MPH (0 KM/H)
2 20 MPH (40 KM/H)
3 60 MPH (100 KM/H)
4 100 MPH (160 KM/H)
TACHOMETER
1 0 RPM
2 1000 RPM
3 3000 RPM
4 6000 RPM
FUEL GAUGE
1 EMPTY
2 1/4 FILLED
3 1/2 FILLED
4 FULL
TEMPERATURE GAUGE
1 COLD
2 1/4
3 3/4
4 HOT


ODOMETER SEGMENT TEST
If a segment in the odometer does not illuminate normally, a problem exists in the display.

ELECTRONIC TRANSMISSION RANGE INDICATOR SEGMENT TEST
If a segment in the transmission range indicator does not illuminate normally, a problem exists in the display.

Thanks to Master Tech at Dodgeforum.com for posting

 

nice bit of info there Raptor, thanks

Regards
Richard

 

- as per #2 the """trip-button trick""" works fine on my 05 Euro Van
- as does the """key dance trick"""