Engine light on. (1 Viewer)

[peatatnaples]

As a theft deterent I wired a remote switch into the fuel pump fused supply. So a fuse jumper in the fuse box with the fuse on the secondary position, a feed and return wire to the switch and the return wire into the original fuse slot. This works as it should switch in off position engine does not start. So far so good but now when the engine starts I get a warning "check engine" and the engine light comes on. Remove fuse jumper and replace the fuse all OK with no warnings. Any suggestions? Oh its Fiat Ducato based Swift 604 2017 build

 

[The Coops]

Perhaps a trickle feed somewhere being interrupted by the switch?

 

[oldiesontour]

I intersected fuel pump feed on top of tank and fitted a remote control switch ...works fine no warnings

 

[Pausim]

Modern vehicles seem to have something called a canbus which controls everything (possibly). I totally don’t understand the system at all but it wouldn’t surprise me if it was having a hissy fit because it has detected something it wasn’t expecting.

Edit. Please feel free to shoot me down on this because I really don’t know what I am talking about.

 

[gus-lopez]

Like, oldiesontour , you would be better cutting the live feed before the fuse, rerouting it via your switch & then back to the fuse holder so leaving fuse where it is.

^{_{Subscribers  do not see these advertisements}}

 

[Itsme]

I think it’s to do with the Canbus - I understand it monitors via voltage drop in the Circuit?

 

[peatatnaples]

There was a time when I understood vehicle electrics rather than modern vehicle electronics. I did wonder if an extra length of cable may upset thngs.
Oldiesontour can I assume you used a relay/switch so no extra wire run and the relay control cable is independant of original circuit. I did look at the top of the fuel tank but with no wiring diagram did not know which wire to cut into. I would be no good a defusing explosives!

 

[the1andonly]

As additional security use 2 switches in series one accessable for daily use tother well hidden for long periods of parking up.

 

[Peavy]

Please feel free to shoot me down

I believe you're right.
When a headlight fails, the can bus detects it and you get a warning somehow, so I believe it would also detect an unexpected cutoff in the fuel pump.

 

[Warwick Hunt]

As a theft deterent I wired a remote switch into the fuel pump fused supply.

Does it work?
I tried disconnecting the fuel pump on my X2/50 and it made no difference
The mechanical fuel pump on the engine sucked the fuel through
Apparently the electric fuel pump is only needed for priming the system, or when the diesel is cold and thick

^{_{Subscribers  do not see these advertisements}}

 

[gus-lopez]

The mechanical fuel pump on the engine sucked the fuel through

that is on the back of the diesel pump & has a solenoid in front/built in to it.That is the one that you have to cut the supply to.

 

[Warwick Hunt]

that is on the back of the diesel pump & has a solenoid in front/built in to it.That is the one that you have to cut the supply to.

Ah I see, Thanks
I just pulled the plug off the electric fuel pump under the small manhole cover in the floor - made no difference.
Didn't look at the one on the engine.
So I put the secret switch in one of the two thin wires that runs from the antennae coil around the ignition switch, to the ECU
It uses this coil to communicate wirelessly with the chip in the key
On my X2/90 the wire is grey/white, but in my experience the colours used in Fiat Ducato looms seem to vary according to whatever colour wire they have to hand!
You can tap into it at the base of the steering column
With the switch off, the padlock light on the dashboard comes on and it will not start.
On the X2/50 it turned over without starting, wheras on the X2/90 it won't turn over.
Its low voltage and current so connections have to be perfect - but it added about another 8 metres of wire to go through (4 metres each way) which has no effect.
Occasionally I switch it on, but the padlock light stays on and it does not start - apparently the switch is not making perfect contact being an ordinary 240 volt switch instead of gold plated contacts for low voltage and current like they use in high end electronics like mobile phones.
I switch it on and off again and then it starts.
The switch only prevents it starting - once it starts it keeps running if I turn the switch off.
Just another line of defence if a thief gets the keys.