Electric Gremlins.

[THORNOGSON]

Although on a Chimaera, this problem could occurr on any car.
The reversing light does not illuminate. Disconnecting the connector in the boot, there is 12.5 volts present. There is continunity from the disconnected connector through the bulb. Therefore it should work? Have also tried another bulb and bulb holder which test good but to no avail.
Anbody habe any idea what is going on?
Graham.

[chris watton]

It could be the reverse switch on the gear lever/box, I had the same prob

[THORNOGSON]

switch must be ok as there is 12 volts at the connector 6 inches away from the bulb.
G.

[tvrbob]

Depends on the wiring. Most reversing light systems switch the negative feed so the 12v is a permanent feed.

[Martin_S]

THORNOGSON said:

switch must be ok as there is 12 volts at the connector 6 inches away from the bulb. G.

Not necessarily...I don't have a Chimaera wiring diagram to hand, but normally the circuit goes:

12V supply>>>bulb>>>gearbox reverse switch>>>EARTH

In other words, there is always a 12 volt supply at the bulb, but the bulb doesn't illuminate until the gearbox switch completes the circuit by allowing it to earth.

Check for continuity to earth on the non-live wire, with/without reverse selected. Obviously, you should have continuity to earth when in reverse gear, no continuity when not.

Edited to add: like wot Bob just said



>> Edited by Martin_S on Thursday 17th February 23:27

[THORNOGSON]

thanks guy's, I knew there must be a rational explanation, I will go and test it now.
G.

[THORNOGSON]

Is the switch accessible from underneath the car as my ramp is in the way of the gear box, or do you get to it from above?
G.

[chris watton]

THORNOGSON said:

Is the switch accessible from underneath the car as my ramp is in the way of the gear box, or do you get to it from above? G.

It's not that easy to get to, When a guy changed my gearbox, he noticed the switch was just 'hanging' in place, and not secured, we also checked the wireing to the reverse light before finding out it was the switch, and it was fine, like yours.