I have a 1991 190e 2.6L. The blinkers, horn, and temp control system recently stopped working. Fuse #11 blows as soon as the acc. circuit is activated. The problem arose at the end of a 1hr drive. I started checking some of the circuits but was unable to find any shorts. Any advice would be much appreciated.

One trick you can use to help the troubleshooting is to connect a 12V test light in place of the fuse. As long as there is a short circuit (or very heavy current draw) the light will glow, and once you have isolated the short the light will go out. This does two things... it allows you the luxury of working on it while the circuit is energized, and it gives you a visual indication of when you've found the problem.

Most short circuits happen at connectors that are subject to motion, heat, or corrosion. I'd say lamp sockets are a prime candidate, but if it's only the turn signals on the circuit, the fuse shouldn't blow until the turn signals are activated. If the auxiliary coolant pump (for the heater) is on that circuit, that could be a problem also.

Good luck!

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1987 W201 190D

Thanks for the tip on the light bulb. That might provide enough resistance to keep the circuit from burning up.


The circuit does have several other components as well. In addition to the ones listed above, it also contains the Warning System, which I don't really know what or where that is.

Yes, it absolutely will.

It will also drop the voltage enough so that probably nothing else on the circuit will work, but you'll be able to see when you've isolated the short.

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1987 W201 190D

Friend, First I would disconnect the aux. coolant pump under the hood. Next I might look for clues in the way the vehicle has been operated ie any consumers not usually operated. This fuse supplies many consumers. good luck

Isolate the climate control fan by pushing the '0' button to turn the fan off. Since excessive current draw is a symptom of the blower failing, if the fuse holds, this is your problem.

Steve

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'91 MB 190E 2.3
'08 RAV4 Ltd 3.5
'83 Lazy Daze m'home 5.7

dpkreuze,
I will give it a shot. As far as i can tell nothing has changed in the operation of the vehicle except the installation of a new power antenna which still operates with the blown fuse.

sbourg,
I tried pressing "0" with no luck. I am in the process of removing the entire control unit from the circuit to verify that it is no in the climate control. I will try to pull the fan or at least disconnect it if I can get to it reltively easily.

>


Blower motor has an Independant/seperate Aux fuse F15 outside the fuse box.
Blower motor draw would not be in the circuit he is having a problem with.
But it could be the regulator.
Unplug the regulator 3 wire feed on the firewall , behind the brake booster and try it. [ R/Blk/Yl]

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A Dalton

Ok..........Does the fuse blow as soon as it is installed and try to fry the fingers? Or............ do you turn the ign. key? If so to what position to cause the overload? I would retrace the steps taken to install the ant, just in case.

When the key is turned to ACC or ON the fuse blows. I can check the antenna but it was installed over a month ago and I havent had any probs. Even with the fuse blown the radio and antenna work fine.

fuse 11 also supplies the hazard switch, dome lamp electronics, and horns (steering wheel)

hazard switch still works, so that leads me to believe that it is not in the blinker system either.

Hazard switch is complicated, when it is on, it gets current through Fuse 12. Off, it connects to Fuse 11. I wonder if the fuse still blows when the hazard switch is on.

Also, as someone else pointed out, the dome light system is on fuse 11. That includes the vanity mirrors. Dome lights and such are made like crap and can easily short out. I'd look at the sunvisor clip contacts and the dome light contacts. Could also be front door switches - another moving part prone to water intrusion and lots of wear and tear. (Rear switches seem to be on fuse 12). The warning buzzer's also on the circuit and is an electromechanical device.

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1987 W201 190D

Finally got some time to do some more troubleshooing. The hazzard has no effect and is listed as running off another fuse. The door buzzer and dome lights are still operational, even with the fuse blown. The aux water pump had corroded terminals but was not the cause of the short. Next I am going to move onto the climate control system and the blower motor.

I'll have another look at the wiring diagram tomorrow, but as I recall the dome light gets its power from fuse 11, so if it works when fuse 11 is blown, something is seriously amiss.

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1987 W201 190D