3rd Brakelight Installation Advice
12-30-2005, 10:03 PM
#31
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Alan,
I really appreciate your input. I'm going to figure out what you are talking about (X-bus on 12v bus?) and then consider it.
Until then, I'm going to try running it in parallel first.
I really appreciate your input. I'm going to figure out what you are talking about (X-bus on 12v bus?) and then consider it.
Until then, I'm going to try running it in parallel first.
12-31-2005, 04:13 PM
#32
Rennlist Member
The bulb check system is pretty sensitive... I would think that you would want to tap into both brake circuits to activate the relay, and prevent feedback between the two circuits with a pair of diodes.
12-31-2005, 04:41 PM
#33
Electron Wrangler
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Dave,
I assumed the 3rd brake light would have its own line from the bulb monitor unit too - but on mine its just in parallel with RHS. I looked for a jumper to the bulb monitor to configure it for ~2x the load on RHS but not obvious if its there, maybe it was an updated module in later cars - seems a bit odd... The brake light switch feed to the bulb monitor would be a good relay coil source (before th monitor - same sense). Could probably even use this switch feed directly to the center rear light...?
Glack - the brake lights, front wipers, headlights, etc are all fed off the X-Bus (the accessory bus). Operates with key in position 2 & 3 clockwise. Off in positions 1 (off) & 4 (starter). You'd want the center brake light to do the same so don't use the ignition bus (15). If you have the workshop manuals - you'll see it on the fuse panel (central electric) page.
Alan
I assumed the 3rd brake light would have its own line from the bulb monitor unit too - but on mine its just in parallel with RHS. I looked for a jumper to the bulb monitor to configure it for ~2x the load on RHS but not obvious if its there, maybe it was an updated module in later cars - seems a bit odd... The brake light switch feed to the bulb monitor would be a good relay coil source (before th monitor - same sense). Could probably even use this switch feed directly to the center rear light...?
Glack - the brake lights, front wipers, headlights, etc are all fed off the X-Bus (the accessory bus). Operates with key in position 2 & 3 clockwise. Off in positions 1 (off) & 4 (starter). You'd want the center brake light to do the same so don't use the ignition bus (15). If you have the workshop manuals - you'll see it on the fuse panel (central electric) page.
Alan