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Alternator light on instrument cluster not lighting after reversing battery terminals
took the battery off my W124 200D to start my sons car. Put it back and without thinking, reversed polarity. Sparks from battery terminal so quickly realised mistake and connected the battery the right way. Turned the key to ignition and gave the glow plug 15 seconds to warm up. Started the car alright Noticed however that Lights A & B ( battery and ???) do not illuminate as they used to when the key is turned. Stereo does not work as well. Suspect that alternator does not charge as well.
Could it be a fuse? Fuses look okay. Or Alternator diodes fried due to reverse large fault current?
How does one check the alternator?
What do I do to make those two lights come on? Lights A & B normally light up (yellow) when key is in ignition position and glow plug is heating up. After reversing battery terminals they do not light up anymore Fuses look okay
The is fuse in the rear of the speedo,, to get at it you need to pull the console out of the dash,,, the fuse will look like the other bulb holders only it will be another colour,,, mine is red . But first check your fuse on top of the over voltage protection relay . But if you are lucky it might just be the inciter bulb for the alternator blown thats the oner that goes out as you start the engine . Might need to checge the over voltage protection relay that gets fried first .Then check the voltage from the alternator . Transistor in the alternator get fried if this wrong polatity is done .
Got a technician to come home and dismantle the alternator.
Took it away and changed the two bits that have been arrowed.
Soon as he put it back, all relevant lights on the instrument panel resumed normal operation
Happy days are here again
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