Technical Indicator relay

[Lawrence53]

I have an intermittent fault with the r/h rear indicator. The bulb is ok, but the yellow light warning comes up on the panel, and I then have no rear indicator r/h side and if you press the brake pedal the mirror indicator lights up. I have checked the earths.. This problem will then disappear after a while and then come back. I suspect it may be a relay but cannot find where it is. This is a 2009 Ducato. Many thanks.

 

[Communicator]

I am not an expert on post 2006, x250, models. @Anthony489, who owns an x250 is much better versed than myself.

It is my understanding that there is no discrete flasher relay, as this role is undertaken by the Body Control Module, or BCM.

The BCM will monitor bulb current, and raise an alarm if the current is outside set limits. Taken on its own, your direction indicator fault could be due an intermittent contact in the wiring or bulb, and this could also be a partial short circuit witthn the bulb. Changing the bulb is relatively cheap.

The fact that pressing the brake pedal illuminates the indictor on the mirror could still be due to a faulty earth connection causing the brake light current to return via that indicator, and then others in parallel.

Another possibility to consider could be a chafed wiring harness.

 

[Lawrence53]

I am not an expert on post 2006, x250, models. @Anthony489, who owns an x250 is much better versed than myself.

It is my understanding that there is no discrete flasher relay, as this role is undertaken by the Body Control Module, or BCM.

The BCM will monitor bulb current, and raise an alarm if the current is outside set limits. Taken on its own, your direction indicator fault could be due an intermittent contact in the wiring or bulb, and this could also be a partial short circuit witthn the bulb. Changing the bulb is relatively cheap.

The fact that pressing the brake pedal illuminates the indictor on the mirror could still be due to a faulty earth connection causing the brake light current to return via that indicator, and then others in parallel.

Another possibility to consider could be a chafed wiring harness.

Thanks, I'll give the earths another look round. Incidentally used the van this morning and everything is fine.

 

[Anthony489]

Hi Lawrence

As Communicator notes, the indicators on this age of vehicle are all driven by the Body Control Module (BCM). There are individual wires running to all 6 indicators, but I suspect the rear and mirror may be commoned together within the BCM. The flashing will probably be achieved electronically, with just a sounder to give an audible tick.

The only place where there is shared wiring between indicator and brake lights is in the rear lamp clusters, which have only one earth pin on the multiway connector and then a black wire to an earth stud at the rear of the vehicle. In my experience, it is the connector to the cluster that gets damp, corrodes, and goes high resistance. Look out for white, green or black deposits on both plug and socket and clean them off. Sometimes a little bending will ensure a better contact. The clusters can be pulled outwards after releasing a couple of plastic threaded "nuts" on the inside. The earth stud (one for both left and right clusters) seems more reliable.

When the earth goes high resistance, some of the brake light current cannot go to ground, and instead finds its way "backwards" through some or all of the other bulbs. It sounds like in your case it is via the rear indicator bulb, across to the mirror indicator bulb, and then through that to ground. Effectively you will have 3 bulbs in series so none of them will get anywhere near full voltage and they will glow dimly. It's the same "christmas tree" effect you get with trailer boards when the single earth pin is dirty.

 

[Lawrence53]

Many thanks, this has given me a few good pointers