Nissan in their infinite wisdom decided to use neutral switch control cables and use twin relays with additional mode change-over not your normal automotive practice but I guess they had their reasons and it works, that is until tracing wiring faults and not knowing the particular way it was configured can make for hours of fun for the un-initiated.

 

So on to the task we had here to sort out, a nice zed with a rather strange headlight switching issue, firstly I must add they had been previous attempts by others to correct this issue with out success.

 

The side lights were fine but the passenger dip beam would not work, the drivers side was fine, the main beams worked but also brought on the previously non working passenger side dip beam! When flashing the main beam only the main beam came on correctly without and dip beam, but with dip and main together the passenger beam came on.

 

Understanding the workings of the Nissan mindset when the circuit wiring was created take a little time to get into but here is a few pointers to start with.

 

Here we have the headlight relays the legend on the fuse and relay cover is a bit of a red herring, the dim relay should really state "dip beam isolator relay" as the other two relays marked headlights are actually for the main beam and are also for the dip beam, but only when the dip beam mode relay is operating...? confused you should be!!

 

 

 

 

So a quick check of the fuses and relays did not reveal anything odd, however the passenger side dip beam had an extra earth cable that had been connected to the chassis, odd but clearly a previous attempt at correcting this or another issue. Removing this and reinstating the correct earth connection now made things worse as the dip beam on the passenger now did not work at all!!

 

At this point

 

So back to the wiring diagram and the circuit is revealed, a strange way of using the relays but basically the main beam relays and the dip are the same but the relay marked as dim relay toggles the earth supply to the individual dip or main beam bulbs, that is why the dips go out when the main is used.

 

 

So now armed with this information it was clear that the dip beam switch on the pod has dual earth outputs to the headlight relays marked left and right, and with the dimmer relay been a change over type the only reason left for the fault must be one of the outputs from the main light switch,the switch was checked and was switching correctly.

 

So back to the relays under the bonnet and at the left hand relay base the earth trigger was not present!! voila!! the solution was simple and effective and negated the effort and time in tracing what must be a broken cable in the miles of loom between the switch and relay base, simply by linking the triggers at the relay end the main and dip beams were do as they should thank fully, needed a lie down after that one!

 

Jeff TT

Nice one Jeff - very useful post as always matey!!

 

Richard:rockon:

Jeff i got lost after the 5th line..great post though:thumbup1:

Great knowledge Jeff!

Can I ask you to revisit my recent post please? " electrical short "

Cheeky I know! But I am bl@@dy desperate mate! Lol

Jeff i got lost after the 5th line :thumbup1:

 

I'll set them up for you Bri..........you lasted twice as long as me :tongue_smilie:.