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Brake Fail Light

Discuss problems you have had or are having with your Z4
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Puggsley2
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Brake Fail Light

Post by Puggsley2 » Fri Jan 13, 2017 12:52 am

The brake fail light on my Z4 has activated yet the brakes work OK. Rotors and pads were changed 12 months ago and brake fluid was changed recently. Any ideas as to a likely cause would be appreciated. I am thinking of buying an OBD tool but have no idea where to plug it it on the Z4. Can anyone out there enlighten me?

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Smartbear
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Brake Fail Light

Post by Smartbear » Fri Jan 13, 2017 1:43 am

Puggsley2 wrote:The brake fail light on my Z4 has activated yet the brakes work OK. Rotors and pads were changed 12 months ago and brake fluid was changed recently. Any ideas as to a likely cause would be appreciated. I am thinking of buying an OBD tool but have no idea where to plug it it on the Z4. Can anyone out there enlighten me?
Hi, the obd socket is in the footwell behind a cover, code reader is best before buying any parts otherwise it's just guessing :?
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e89 Sdrive 20i, plenty of mumbo & good economy-the thinking bears z4
e89 Sdrive 30i, this ones busted, pass me another...
e85 3.0si sold

Puggsley2
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Brake Fail Light

Post by Puggsley2 » Wed May 10, 2017 5:49 am

The problem with alarms continues. First the brake warning flashed on the dash but after a few days it cleared later to be replaced by a stability control unit fail. Again after a few more days that was replaced by an air bag warning light. I gave up trying to fault find and took the car to the local Bosch people. They advise that all faults were cleared by a new one - RCM Code 20 - is now showing on their diagnostics. They have no idea what that is but it seems to be coming from the Light Control Module. Apparently they can only be sourced from BMW and need programming by BMW.

Any idea what fault Code 20 means?

Scooba_Steve
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Brake Fail Light

Post by Scooba_Steve » Wed May 10, 2017 10:36 am

Before spending big money check your battery. The gremlins come out to play but the car will still start, its the cheapest starting point.
3.0si Sport: F10 Illuminated ZHP, Retrofit Cruise, OE Stubby, Gaptech RCH+, Kenwood BT73DAB + Handsfree, HIDs, LED Sidelights, OE LED Number Plate Lights, Custom LED strip bootlight.

Puggsley2
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Brake Fail Light

Post by Puggsley2 » Thu May 11, 2017 9:44 am

Good point and thanks. The battery is a few years old so this sounds like a good suggestion. The car starts etc as though the battery is fine bu even I know thta isn't a good indication. The car is still in the BMW Hospital so I have told the nurse to thoroughly check the battery and I will advise the outcome.
Again thanks

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Brake Fail Light

Post by Scooba_Steve » Thu May 11, 2017 9:47 am

If it is the battery then that could also just be a symptom of a failing alternator. These are easy to check though and would be my first steps as the faults seem to have been random and unconnected.
3.0si Sport: F10 Illuminated ZHP, Retrofit Cruise, OE Stubby, Gaptech RCH+, Kenwood BT73DAB + Handsfree, HIDs, LED Sidelights, OE LED Number Plate Lights, Custom LED strip bootlight.

Puggsley2
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Brake Fail Light

Post by Puggsley2 » Fri May 12, 2017 10:23 am

We checked the battery today and it passed with flying colours. Corroded connections were found next to the battery and many of the error codes disappeared after that. One remains and the workshop computer can't clear it. It shows as "Code 20 LCM" which suggest a fault in the lighting control module. All lights work OK and no reason has been found for the error code to remain. Anyone know what Code 20 LCM means?

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