Main.TrailIndexPage | Electrical Systems | Dashboard Instruments

Dashboard Instruments

This component is part of Electrical Systems.

Main Instruments

  1. Tachometer red mark: excess engine speed range
  2. Turn-signal control lights - green, right and left
  3. Generator (alternator) indicator light - red
  4. Brake fluid warning light, doors open - red (Note: this control light is not used on 230SL cars!)
  5. Odometer (total mileage counter)
  6. Return button for trip odometer
  7. Fuel gauge. R and red warning light: reserve fuel for about 22-25 miles.
  8. Oil pressure gauge
  9. Control knob for instrument lights, or Rheostat.
  10. Telethermometer for cooling fluid; red dot: max. permissible temperature
  11. High-beam control light - blue
  12. Trip odometer (trip-mileage counter)

"C.L." = control lights

Topics covered in other sections but frequently referred to here are:

The Dashboard material is covered elsewhere.


Describe common maintenance procedures, and common faults that may occur. Describe how these may be diagnosed and resolved. Again, include diagrams, photographs and explanations. Where possible, include measures, tolerances, weights etc.

Link to related components where appropriate.

Removing the Dashboard Instruments

Joe Alexander's method:

  • Remove steering wheel (center pad, then 22mm nut, then wheel, notice and make note of the indexing mark on the end of the steering column))
  • Remove dash pad lower left (three screws).
  • Remove bracket holding wiring harness plugs under dash and move it aside (two screws)
  • Reach up into dash and dis-connect small round duct tube going to dash vent and move out of way (just pops off remove one end only)
  • Unfasten tachometer cable (round knurled collar around cable )
  • Unfasten tach bracket knurled thumb nut holding tack in place ( try using wearing some thin leather driving gloves if the nut is very tight)
  • Remove the RPM Gauge from the front of the dash (notice the brown wire with the ring terminal was attached to the tach mounting stud) Don't forget to re-attach this wire during re-assembly!
  • Simply pull the light bulb sockets with wires out of the gauge.
  • Next move to the center cluster (be gentile with the capillary tube attached to the back of the temp gauge.
  • Unfasten the 10mm fitting holding the oil line to the oil pressure gauge. ( do not start engine with line dis-connected or oil shower will begin)
  • Remove the knurled nuts holding the center cluster in place.
  • Center cluster can be move far enough out of the dash to move onto speedometer with capillary tube still connected.
    • If you wish to remove the center cluster all-together, the back part of the center cluster can be removed by also unfastening the small knurled nuts and the small slotted screws on the back of the cluster. The back section can now be lifted off. The engine temperature gauge can now be removed by unfastening its two mounting screws. Leave the temperature gauge attached to its capillary tube and leave it at the dash. You can tie a plastic bag around it to protect the fragile needle if yo like. Again be gentile with the capillary tube.The center cluster can now be removed from the car. Take this opportunity to check the lighting rheostat and all the bulbs.
  • Next remove the knurled collar around the speedometer cable
  • Remove the knurled thumb screw holding the speedometer and bracket in place (notice the brown wire with ring terminal also fastened underneath)
  • Remove the speedometer.
  • Simply pull the light bulb sockets with wires out of the gauge.

Re-assemble in reverse order, don't forget the brown ground wire under the small knurled thumb screws !

Removing the Bezels

You will need to pry off the bezel with a small screwdriver, since it is 'crimped' on. Since the crimp is on the back of the gauge, don't worry too much about what you are doing. Re-fitting requires re-crimping, with some pliers (I wrap those in cloth to not damage the chrome).

Stick's alternative method

The easiest way to do remove the dashboard to get behind the instruments is to remove the chrome vent/grill next to the A post, remove the three screws that hold the duct behind it in place and then you can reach in to remove tach/cluster/speedo. The whole lot can be done in half and hour with no contortionism required, especially if you remove the steering wheel first. The only difficult part is in getting the chrome grill off without breaking the studs.

There is a document in German on that details the removal process for a 230SL. Translation using Google Translate is available here Attach:Removal230SLInstruments.pdf

Removal of additional equipment

I am trying to remove the following from the dashboard, any hints on how to accomplish this?

  1. Lightswitch (do not know how to remove black plastic part)
  2. Cigar Lighter
  3. Ignition Switch
  4. Emergency Flasher
  5. Heater levers (I have removed all chrome from front and unit is loose, do I remove cables from unit, or from where it connects to (heater)?
  6. Center Gauge display (Oil Pressure Gauge, Fuel Gauge and Temperature Gauge). If I am not going to start the car, can I disconnect all wires including oil line, or will it leak?

Joe Alexander: the black plastic part of the light switch will pull straight out after unscrewing the chrome ring. It takes more force than you would think. The cig. lighter can be removed by disconnecting the plug and twisting the plug prong unit on the plug end of the unit. Next a thin 13mm nut can be unfastened to free the retainer and the cig. socket will pull straight out of the dash.

The emergency flasher is removed after the chrome ring is unscrewed. I believe the knob can be left in place while unscrewing the ring? Now the emerg. switch can be unpluged and removed from behind. The heater levers will be a challenge.

Most people remove the cables from the unit. The speaker with grill and the radio also must be removed first. If you have not removed the glovebox yet do so. It will help removal of the cig. lighter, chrome and heater leavers. As you know the dash face chrome around the heater unit must be removed (10mm nuts). Be sure to find the two hidden phillips cable lock down screws. These can be viewed by looking through the windshield from the outside of the car.

Look down the speaker hole and move the top heater controls until the hidden phillips screws are visible. Turning the screws will release the top cables from their post. The little "U" clips can be popped off and the special lock-down ring clips can be removed to unfasten the other cables. Mark the cables if you are not familiar for re-assembly later.

All cables and control flaps and valves should be put into good working order before re-assembly. The center dash display unit is freed by a single thumb screw behind the dash. Getting to it and the speedometer cable is the tough part. I reccomend removing the steering wheel, which is easy on these cars. Access to the gauges and removal of your ignition switch will be made so much easier.

After your center cluster is free, you will have to unhook the oil line. The temperature gauge has a capillary tube which must be handled carefully. I suggest carefully removing the temp. gauge from the cluster and storing it in the dash opening and not disconnecting the unit at the engine. This capilary tube is fragile and the connection at the engine is often weakened by corrosion or previous repairs. The oil gauge can also be removed from the cluster and left in the dash, if you want to start the car.

You may want to tape a small clear plastic bag around these gauges if you store them in the dash to protect the delicate mechanisms. The ignition switch will probably require removal of the speedometer also. The elements involved in the removal of the ignition, are designed to be a little difficult or complex. First the 10mm bolt and nut on the clamp/collar around the stem of the locking mechanism must be loosened.

There is a 13mm nut on top of the unit which will loosen the large "U" strap holding the steering column tight and also holding the ignition in place. There are one or two 13mm bolts under the dash which need to be removed. The padding may need to be removed first? Next turn the ignition key to first position right. Use a good mirror and a light and find the hidden lock button/pin on the ignition steering lock. This is near that 10mm clampping unit, on the steering lock shaft. It is about 3/16" diameter or about 5mm.

Push the pin down and twist and pull on the switch assembly to begin removal. (As stated the ignition must be in the first position to the right or the button/pin cannot be depressed). Now remove the key and finish removing.
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