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Old 27th September 2019, 11:29   #15
Odd Job
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MG ZT 2.0 cdti

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Quote:
Originally Posted by SD1too View Post
Richard; the reason for the suggestion that you check fuse 13 (in the passenger compartment fusebox) is that it is a 12v supply to the Light Switch Module (LSM), as is fuse 25. The LSM controls all exterior lighting including the brake lights. It is therefore possible that, if either of these 12v supplies is missing, the LSM could enter a fail-safe mode and illuminate the brake lights continuously.

However, you have reported that on arrival at work the brake lights had reverted to normal operation. This might indicate an intermittent fault.

Please check these two fuses, numbers 13 and 25, and I also have two questions for you:
  • Are all 3 brake lights illuminated or just some of them?
  • Is the brightness of the brake lamps normal or at the lower level associated with a tail lamp?

You need not worry about the CAN bus because it isn't involved in brake light operation.

Simon
I cant find any fuses blown.

When the lights were on, all 3 stop lamps were the "normal" brightness as if the switch was activated.
I checked all the other lights and everything else was working fine.

I've checked twice a day since it happened and so far, all good.

Richard
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