R33 gtst reverse light not working

[Manur33]

Hi team, my r33 reverse lights just stop working . It’s a factory manual and i check the bulbs they are good. I checked the reverse switch plug on gbox and bridge it, the reverse lights didn't glow. I check the switch with multimeter no voltage coming up. Can anybody shade what could i check next.

[GTSBoy]

Get the wiring diagram. Work out which wires have power and earth and at what times (ie, switch opened/closed). Then grab your multimeter and look for those voltages and work out what is wrong.

[Manur33]

I try to find the wiring diagram but cant actually find it.

[GTSBoy]

They are posted on these very forums about a thousand times.

 

R33_Wiring_Diagram.pdf

[Manur33]

Sorry i dont know how to read it

[GTSBoy]

Find the lamps. Find the battery. Find the switch. Follow the wires (black lines) between them. Print it out on a bunch of A4s and stick it together with tape if you need to.

It's a worthwhile endeavour.

[Duncan]

OK....so to trace that, per the diagram.

You said you bridged the switch at the gearbox and the lights don't turn on. Per p8 that is plug 61 with reference A31. BTW are you sure you bridged the reverse switch because the neutral switch looks very similar....

The "Main Wiring Diagram" is the conceptual one you should start with. Reverse Lights are in the middle of p6. It shows wires LR01 and LR02 go from the reverse lamps (connectors T34 and T38) to the Reverse Light Switch A-31 which you said you bridged to test.

LR03 is the Positive Input to that switch, it joins to MJ01 in the loom with a lot of other Ignition 12v stuff and goes to Ignition Fuse #12 10A.  Ignition Fuse #12 and other things are fed by Ignition Relay R16 (which is located in the Fuse Box at the Driver's knee marked 37 on p11). Power to the Ignition Relay comes from the 65A fuse in the boot FL14.

So to play that all back....you should have 12v at one of the Reverse switch pins with the Ignition on. 

If you don't, check Fuse 12 (I believe it is last on the left column at driver's knee marked "Electrics"), then relay 16 (unlikely to be an issue unless other things are not working), then big Fusable link FL14.  If both fuses and the relay are OK and you don't have power at the switch, you have a power supply wiring issue which might be easiest to fix just by running a new wire to the switch.

If you do have 12v at one side of the switch with Ignition on, you have a wiring (or globe) issue between the switch and the tail lights, or the tail lights are not earthed properly.

[Manur33]

Yes , i check both switch neutral got power but reverse don’t

[GTSBoy]

1 hour ago, Manur33 said:

Yes , i check both switch neutral got power but reverse don’t

Well, the other end of one of those wires should go to ground (maybe via the globe) and the other end should have 12V (maybe having come via the globe). The wire is not solid copper along its full length right now. So..... go looking for where it is not.