In this guide, you will learn about problems that cause Mercedes-Benz issues and how to use a Mercedes-Benz All System Scanner to diagnose cluster problems yourself.
It is not uncommon for the Mercedes-Benz instrument cluster (IC) to stop working or gauges to malfunction. Here is a list of the most common symptoms:
- Mercedes Instrument Custer is dead.
- Dashboard Gauges not working
- The instrument cluster is too dark, hard to see.
- Engine starts, car runs, but cluster stays off.
- Older models suffer pixel issues typically with LCD of a clock or gear display.
- The speedometer, tachometer, fuel, and temperature are not working.
- Turn signal arrows on IC not working.
- Gauges, tach, clock, speedometer, fuel level, coolant level do not work.
The instrument cluster itself may fail. In such cases, the cluster needs to be replaced or repaired by a professional. Mercedes-Benz dealers generally do not repair defective clusters; they only replace them. Finding an independent repair shop that specializes in instrument clusters can save you money.
When you install a new cluster, you need to use a scanner to read and transfer coding to the new cluster. This includes transfer mileage, drive authorization, user settings, etc. This must be performed with a professional scanner such as the Mercedes-Benz Star Diagnostic scanner.
Picture of a good instrument cluster fuse.
If nothing on your instrument cluster works, the problem could be a blown a fuse. If the instrument cluster doesn't turn on, doesn't light up, and none of the gauges works, check the instrument cluster fuse box located on the side of the dashboard.
If the instrument cluster fuse blows, it indicates a problem in the instrument cluster or damaged wire harness.
Low battery voltage can cause instrument cluster problems. The first indication is a warning message stating: "Battery protection, comfort functions temporarily switched off."
This issue is often caused due to a partially discharged battery.
Having to jump-start the car may cause the instrument cluster to malfunction or flicker as well.
If your gauges work erratically or seem to jump, the problem could be a lousy voltage regulator.
Fully charge the battery or replace it if needed for the instrument cluster to operate normally. Some Mercedes-Benz S, E, ML, GLS models have two batteries. The main battery (G1) and a second auxiliary battery (G1/7). Both need to be tested and fully charged.
Jump starting the car incorrectly can cause permanent damage to the instrument cluster.
Check the ground (negative) connection at the battery terminal.
A short in the wiring harness or loose ground connection to the instrument cluster can prevent the instrument cluster from turning on. This may be the case, especially if you are experiencing intermittent cluster problems.
The terminals where the wire harness plugs into the instrument cluster may develop corrosion. Remove the cluster and check. Inspect both the terminals on the instrument cluster but also the connector.
If corrosion is present, cleaning the connections can bring the instrument cluster back to life.
If your instrument cluster background lights don't turn on or are too dim, the headlight switch may be defective. Try setting the headlight switch to AUTO or ON to see if any of these two settings work.
Also, remember to turn up the instrument cluster brightness.
One gauge is not working.
If only one of the gauges does not work, the problem may not be the instrument cluster at all.
For example, if the fuel gauge does not work or intermittently works, the problem typically is with the fuel level sending unit installed in the trunk instead of the instrument cluster.
If you have more than one gauge not working, the problem may be a defective SAM unit.
Test Mercedes-Benz Instrument Cluster
There are several tests that you can carry to check Mercedes-Benz's operation.
Test you can perform:
- Turn on all the dashboard lights.
- Activate all gauges/needles
- Check instrument cluster background lights.
To carry out proper diagnostics, you will need an OBD2 scanner capable of diagnosing the Mercedes-Benz instrument cluster module.
Scanners that you can use:
- Connect your scanner to the diagnostic port located under the dashboard.
- Turn on the ignition.
- Select Mercedes-Benz > Chassis
- Go to Control Units
- Select Information and Communication
- Select Instrument Cluster
- Select Live Test
- Select the test you want to perform.
- Test gauges
- Test instrument cluster background lights
- Test cluster colors
- Test all lights
- Test instrument cluster speaker
Troubleshooting Mercedes-Benz instrument cluster issues can be very challenging. In some cases, it may take several hours to find the root cause of the problem.
Can I install a used cluster?
You can, but the mileage will not show on the instrument cluster. It will display as ------. Used instrument cluster mileage is very challenging to program.
The EEPROM memory needs to be erased before the mileage can be corrected. Very few repair shops will be able to reset the mileage and program a used Mercedes-Benz cluster.
If there is an instrument cluster open recall for your Mercedes-Benz, the dealer will fix the problem described in the recall free of charge, even if your vehicle is out of warranty.
Check if there is an open recall by going to the National Safety Highway Administration website.