Technical Left Dipped Headlight and Fan Issue

[BartsimpUK]

Good afternoon Fiat Gurus,

I bought a 2014 Ducato based motorhome (Carthago C Tourer) in Feb and all has been good with a couple of thousand miles under the belt. Last weekend the left dipped headlight stopped working. Checked bulb and fuse (also replaced both) but no joy. After some internet digging thought the issue may be to do with the T02 relay in the engine bay fuse box. To get to this I removed the T07 relay. Couldn't see anything obvious with either so replaced the T02 but, when I replaced the T07 relay the engine fan immediately sprang into life until I removed the relay again. Now there is a check engine message on the dash.

I've replaced both relays (incase I'd damaged them somehow) but no change, the fan runs continuously.

Therefore I have 2 problems, priority 1 - the fan. and then back to the original problem of the light not working.


I'm really hoping you legends can help as I've been told by an auto electrician that he can't seem me before July!!!

Thanks

 

[Communicator]

Good afternoon Fiat Gurus,

I bought a 2014 Ducato based motorhome (Carthago C Tourer) in Feb and all has been good with a couple of thousand miles under the belt. Last weekend the left dipped headlight stopped working. Checked bulb and fuse (also replaced both) but no joy. After some internet digging thought the issue may be to do with the T02 relay in the engine bay fuse box. To get to this I removed the T07 relay. Couldn't see anything obvious with either so replaced the T02 but, when I replaced the T07 relay the engine fan immediately sprang into life until I removed the relay again. Now there is a check engine message on the dash.

I've replaced both relays (incase I'd damaged them somehow) but no change, the fan runs continuously.

Therefore I have 2 problems, priority 1 - the fan. and then back to the original problem of the light not working.


I'm really hoping you legends can help as I've been told by an auto electrician that he can't seem me before July!!!

Thanks

2014 was a model change year, so is the base vehicle an x250, or the later x290 model. Does the conversion use the original headlamps, and wiring, or has it been modified? The small amount of information that I hold for the x250, shows that the dipped headlamps are contolled by relay T01 on the cab fusebox, and not T02 which controls the main beams. As the relays are common to both headlights, and are only single contact, then I can see no reason to suspect the relay. A fuse or wiring fault would be more logical.
As you have a check engine light illuminated, have you had the fault code(s) read?

 

[BartsimpUK]

Hi. Thanks for the response. I think it is the newer version as, as far as I can work out, the fuse box layout changed at this point and i
Seem to have newer layout. So, in the cab the left dipped headlight is on fuse F13.

The headlights are standard fit and it doesn’t look like any wiring has been changed. I plugged in a cheap OBD 2 reader which came up with the P0480 code (cooling, but no mention of lights). There is also a check engine message on the dash when I start the engine.

I’m trying to get it booked in with a Local mechanic but availability is proving difficult at the moment, but thought I’d check with you guys to see if this is a know / easy self fix.

Again thanks for taking the time look at this post.

 

[Communicator]

Hi. Thanks for the response. I think it is the newer version as, as far as I can work out, the fuse box layout changed at this point and i
Seem to have newer layout. So, in the cab the left dipped headlight is on fuse F13.

The headlights are standard fit and it doesn’t look like any wiring has been changed. I plugged in a cheap OBD 2 reader which came up with the P0480 code (cooling, but no mention of lights). There is also a check engine message on the dash when I start the engine.

I’m trying to get it booked in with a Local mechanic but availability is proving difficult at the moment, but thought I’d check with you guys to see if this is a know / easy self fix.

Again thanks for taking the time look at this post.

Given recent activity around the engine bay fusebox, the only hypothesis that I can offer at the moment, and which may be possible, is that the negative coil connections for relays T02, and T07 have somehow become shorted together, inside the fusebox. The fan relay T07 probably has its coil positive connected to permanent 12V, while T02 will be ignition controlled. The postulated short would allow both relay coils to operate in series, with the current returning via other ignition controlled circuits. (Fiat do not adhere to the Bosch convention for relay coil connections, and use only resistor suppressed coils which can operate in either direction of current flow. If the ignition is not on, and hence the ECU not powered there will be ample routes to earth for the reverse energised headlamp relay coil.

Switching on the ignition, or removing either of the relays should break the circuit.