Trailer wiring - right hand indicator

[Road 2 Nowhere]

Towing a caravan - have diagnosed that the right hand indicator (on van only) not working - traced it back and not working at 9 pin round on vehicle. I only have resistor on RH indicator so it is not sensing trailer.

Had a look and doesn’t appear to be fused?

Any advice or tips on where to trace back in vehicle?
Appears loom may run into rear quarter panel?

[RANDLOVER]

Perhaps the resistor has popped or there's a switch for the resistor. What car are you using and have you used this car and van combo before?

[Tombie]

Towing a caravan - have diagnosed that the right hand indicator (on van only) not working - traced it back and not working at 9 pin round on vehicle. I only have resistor on RH indicator so it is not sensing trailer.

Had a look and doesn’t appear to be fused?

Any advice or tips on where to trace back in vehicle?
Appears loom may run into rear quarter panel?

D4s use Mosfet and fusing up front at the CJB (behind glove box)

[Road 2 Nowhere]

Perhaps the resistor has popped or there's a switch for the resistor. What car are you using and have you used this car and van combo before?

Have been using D4/van combo for 7mths towing around Aus.
The resistor is on the Van wiring of RH indicator that I installed.

When I tested with multimeter at the 9 pin round on car that pin is not pulsing,
fault is upstream of there. I assumed fuse or the electrical component that causes the flashing but cannot find either behind the glovebox.

Thanks RANDLOVER for your help

[Road 2 Nowhere]

D4s use Mosfet and fusing up front at the CJB (behind glove box)

I’ll have a better look behind the glovebox.
I take it MOSFET is the electrical component that causes the indicator flashing, are there seperate for the trailer brakes? As the car RH indicator is still working.

Thanks for you help Tombie

[RANDLOVER]

I’ll have a better look behind the glovebox.
I take it MOSFET is the electrical component that causes the indicator flashing, are there seperate for the trailer brakes? As the car RH indicator is still working.

Thanks for you help Tombie
There is also a fuse box in the rear, the following post refers to a D3 but I can't see a D4 being much different...


I am a D3 owner and the brake light fuse is number 1 (7.5A) inside the removable cover in the left hand rear of the vehicle. I.E. open the tailgate and stand behind vehicle and reach in to the left and check.

I don't know if there are fuses there on the D4. However the info should be in the owners manual if you have one.

[BradC]

According to the early D4 wiring diagram I have here the Brake / RH & LH Indicators are driven directly by the BCM and there are no fuses. The only fused outputs to the trailer sockets are Tail lights, Reverse, IGN and Batt pins.
There do appear to be 2 connectors in the harness between the socket and the CJB though, so it could be one of those.

[V8Ian]

You could go old school.

193782

Sorry, I'm being flippant.

[BradC]

I take it MOSFET is the electrical component that causes the indicator flashing, are there seperate for the trailer brakes?

In this context a MOSFET is a semiconductor electronic switch. Like a silicon version of a relay. These particular MOSFETS are more of a complicated sub-module that also have current sensing built in, so if the circuit is over-current they have a "soft" trip out rather than a fuse. They also have the ability to report current draw which is what the car uses to detect a trailer connection.

They are completely separate to the lights on the vehicle.

Have you scanned for faults? It's entirely possible there may be a fault logged for that circuit.

[Globetrotter]

Do you have the standard LR trailer wiring, that is a Black round socket and a White round socket. If so I think there should be a fuse panel and connectors in the LH rear quarter panel. Have you checked the trailer wiring by applying 12 volts to indicator wire and see if it lights up.

[AK83]

.....

When I tested with multimeter at the 9 pin round on car that pin is not pulsing,
fault is upstream of there. I assumed fuse or the electrical component that causes the flashing but cannot find either behind the glovebox.

....

Did you confirm that the pin on the connection side not getting power, or the wire on the backside not getting power?
Apologies for being pedantic, but it's very common for the screw connector on the wire side(back side of the pin) to fail in it's connection.
As you said you tested the pin, and not the wire ... you could easily have power at the wire, just not getting to the pin.

Very common problem on trailer plugs.

[RANDLOVER]

Do you have the standard LR trailer wiring, that is a Black round socket and a White round socket. If so I think there should be a fuse panel and connectors in the LH rear quarter panel. Have you checked the trailer wiring by applying 12 volts to indicator wire and see if it lights up.

It seems the D4 use "smart fused" MOSFETs vs the D3 but they may have turned the rear fuse box into a joint box or have plugs there to make the wiring loom continuous, so worth checking, Although as Ak83 Arthur said a break in the wiring or corrosion is more likely to be on the exterior of the vehicle.

[Tombie]

Did you confirm that the pin on the connection side not getting power, or the wire on the backside not getting power?
Apologies for being pedantic, but it's very common for the screw connector on the wire side(back side of the pin) to fail in it's connection.
As you said you tested the pin, and not the wire ... you could easily have power at the wire, just not getting to the pin.

Very common problem on trailer plugs.

D4 plugs are bonded, they dont come apart at the wiring connection...