I have a 92 300TE 4Matic. I really like the photographs I have seen with the AMG add on driving lights below the bumper.

However this creates questions for me:
If using this AMG Style lower bumper does one still have access to the tow hook?
How are the driving lights operated? A separate switch?

I have also seen pictures of several 124 wagons with a tow bar hitch receiver. I cannot find that for sale anywhere. Where are they being produced? (At most I would be towing a small motorcycle trailer with a Honda Goldwing motorcycle.)

My outside temperature gauge always reads anywhere between 108 and 136 degrees. It also will not show anything if the headlights are turned on.
Should I be looking to replace the temperature sensor or is this a display box issue? What testing can be accomplished to determine where this challenge is located?


Thanks,
Dave H...

I can't offer specifics for your car but here is some general info.

If you can't reach the tow hook with a new bumper, get a car trailer tie down strap. These have an eye at each end allowing the strap to be wrapped around the lower control arm.

MB driving lights ( on modern cars at least ) are operated by turning the headlights on then pulling the headlight switch out one click, pulling to the second click turns on the rear fog light.

The outside temp problem sounds like a grounding issue. These cars might have a instrument cluster board problem it I recall correctly. The temp sensor is in the front bumper area.

Thank you so much for taking the time to reply and provide some valuable input.

I knew of the Tow Straps you mention but had not even thought of using them here. Thanks.

On the 92 with one pull of the headlight switch I engage the vehicle's Fog Lights.

I have just about come to the conclusion to install a separate switch, located in a seven hole cut out of my upper center console to operate the driving lights by. I have just purchased another Air Circulation switch and do not believe it will be much of a challenge ??? to just have a decal printed out to replace the air circulating icon with a driving lights auxiliary one.

I have located the outside temperature sensor. Going any further though with the possibility of an "instrument cluster board problem" might just be a little over my head.

Thanks Again,
Dave H...
aka Professor

When you wire the fog lights up, use a relay ( Bosch cube style is popular ) so high current does not flow through the switch. There are lots of diagrams floating around on how to wire a relay.

Thank You I had not thought about the necessity of a relay.

I will attempt to find the diagrams to assist me.


Dave H...
aka Professor

If you get a standard 30A Bosch-style relay, wiring is dead easy.

Pin 30 gets fused power from the battery.
Pin 85 is grounded.
Pin 86 gets power from whatever switch you're going to use.
Pin 87 powers your lamps.
Pin 87A is left open.

A few other design considerations.

Some relays have a diode across the coil to limit the inductive spike when the relay is shut off. There are a lot of diagrams that interchange power / ground on 85 - 86 and I don't recall what is correct.

Put the relay under hood so high current wiring is minimized.

The fuse goes as close to the power source as possible as wiring up stream of the fuse isn't protected. ( Unless it eventually leads to a distribution fuse.)

You will need some sort of indicator to show the lights are on.

Power feeding your switch should be hot only when the ignition is on, this prevents the lights from being on while the car is off.

^ Good stuff, all of the above.