K6JRF at the mic K6JRF's Page
formerly W6FZC

My Mercedes Benz
S500 Coupe

K6JRF's MB S500 Cpe
(New: Mar 22, 2007)

Analyze and Troubleshoot "Check Engine" MIL and Electronic Control Units (ECU)!

Instrument Cluster (IC) Tests

Think your Instrument Cluster (IC) is broken?? Some of the functions not working?? Read on to find out how to figure out what's wrong!

If you are not reading the car's road speed - or - the oil pressure shows "0" - or - if the mileage economy shows "0", then there's an easy way to test the IC to be sure it's ok. The test mode described here allows you to see if the IC is working as it should. Hopefully, you'll find it's good!

The IC Test Mode disconnects the IC from the external sensors (oil, speed, etc) and uses internal voltages to test each IC function to determine whether the IC has a problem, or whether the external inputs to the IC are at fault.

To test the instrument cluster, you'll see a small "button" in the center of the "clock" knob as the picture shows.
IC_service button
To enter the IC Test Mode, first start the car, then with the tip of a pen or paperclip, press the button for at least 5-6 seconds. The odometer and the local milage display should change from showing mileage to the following "-------". The IC is now is the Test Mode. Within 5 seconds, pull out on the clock setting knob and rotate briefly to the right. Do this to advance to each subsequent mode.

The readout is in the form of a number, then the 'function', so for IC Test #1, the readout is "1    80 ".   "1" = Test #1 and "80" is the size of your gas tank in Liters. Mine read "1    87".

IC Test Modes
There are 9 testing modes for the cluster:
1 - shows gas tank size (liters)
2 - momentary fuel consumption (litres per hour)
3 - engine oil pressure (bar)
4 - engine rpm (rpm)
5 - engine oil level (0 = level OK, 1 = not OK)
6 - activates oil pressure, economy, tach, speedo, fuel level gauges to 1st quarter of travel - display also reads resistance of outside temp gauge in K ohms
7 - oil pressure, economy, tach, speedo and fuel level move to 2nd quarter of travel
8 - economy, tach, speedo and fuel level move to 3rd quarter of travel. Oil pressure remains at 2nd quarter
9 - tach, speedo and fuel level move to 4th quarter of travel - oil pressure remains at 2nd quarter, economy remains at 3rd quarter

IC_Test Mode '8'
The picture shows "test mode-8". How about being at red-line while idleing in the garage??

This test should allow you to figure out whether the cluster has a problem, or whether the external sensor is not working properly.

To exit the IC Test Mode, turn the ignition off. After re-starting the car, it will revert to the normal mode.

Send me Email Icon with your comments