General Reverse Relay location

[dmf]

Hi

I have encountered an electrical problem with my 2.8JTD RHD Ducato 15 - 2005 model, Lunar Roadstar MH.

Basically, I have lost reverse lights (3) and the use of both reverse cameras, and habitation step won't auto retract on engine start up. When Key is entered in ignition accessory stage there seems to be momentarily power to the reverse camera circuits,but as soon as I start engine the reverse power circuit goes dead. I have checked all fuses and appear to be OK - as there isn't a fuse circuit for reverse, I guess that it must be a dedicated Reverse relay that is faulty. Unfortunately I have no idea where to look/ or find the relay that governs the Reverse circuits switch 'on and off' functions.

Can anyone guide where to look for it? Thanks for reading

 

[Crossingkeeper]

I can only make some basic suggestions:

The retraction of the habitation step happens whether or not the van is in reverse gear but is controlled, as you say, by engine start-up.

This wiring for this, as for the reverse cameras, will be an add-on to the vehicle loom, while the reverse lighting circuit, though modified, will be part of the original wiring circuit.

Therefore, if all the faults appeared simultaneously, it is probably not specifically down to the reverse lighting circuit (which I believe is fused and controlled by the gearbox mounted reverse light switch) but probably a degraded connection 'somewhere' in the habitation wiring. It would be worth checking that the fridge will still run on 12 volts when the engine starts as there are usually a bank of relays and connectors installed by the converter under the bonnet, usually near the battery, which are connected to the ignition and/or alternator circuits and can give problems.

HTH.

 

[dmf]

I will check out your suggestion - the problem occured when I started the engine with it in reverse gear ! Before then all was OK.
I cannot find a fuse for the reverse lights - have checked all fuses added by Lunar and they are all OK - hence my thought it must be the governing relay.

I will check out the fridge 12v supply - as the MH is at storeage site and it's snowing here in Dover, I won't be able to check for a few days.

I will update this post when I have checked out your reply/ suggestions. Thanks

 

[dmf]

I have been to the Mh to check out advice received. The 12v circuit to the fridge and habitation area /lighting, roof mounted Camos (in motion model) all cease to work when the engine is running. With the enging off the Fridge internal light is working (so I assume that the fridge unit is also!)and all habitation lighting works including CAMOS. I swopped two relays over in the engine bay close to starter battery - this didn't make a difference.

AS everything 12v in the habitation area appears to work when the engine is off, I assume that the fuses to them are ok- so my problem appears to be down to engine start up stopping supply to the items not working

habitation 12v circuit
Step retraction
Reversing light activation
power to 2 reversing cameras


The circuits for heater fan windscreen wipers, remaining vehicle lighting seem to be OK.

Is it possible for their to be a fault on the ignition switch/relay?


What next can I check out?

Thanks for reading and your interest/help

 

[Crossingkeeper]

I've had a look on my eLearn Disc and the most useful section seems to be this:

Operational Description
The reversing light activation signal leaves switch I020, located in gear casing, ignition-operated (INT/A) via a connection between ignition switch H001 and pin 48 connector C of under-facia junction unit B002. Power is supplied to short-circuit junction D097D - pin 1- via fuse F31 housed in the junction unit. The short-circuit joint supplies, in turn, reversing light switch I020 from pin 5.

When reverse is engaged, switch I020 closes - across pin 1 and pin 2 - and sends a signal to short-circuit junction D097D, pin 7, that governs activation of the bulb housed in tail-light F031.

A signal also comes from parking sensor control unit (see function E3090).

Unfortunately there is no clue as to what the 'short-circuit junction D097D' is but the wiring diagram shows this as a box with all other components wired from it and the location seems to be under the dashboard on the nearside.

The elearn manual for the 2002-06 Ducato is available as a download from the forum if you want to have a look for yourself (but the procedure is equally technically challenging as sorting the lights!!)

PS if you have manual energy selection for the fridge, the 12 volt setting should only work with the engine running (I'm not sure how you could check this if it's automatic selection)

 

[dmf]

Thank you for your reply and taking the trouble to look up the manual references in your post/replyl.

I had come to the conclusion to take a look at fuse F31 - if that is ok then I guess that it must feed relays which will need to be found and investigated.

If I cannot trace the problem I will have to get an Auto Electrican to find the problem.

I'll let you know how I get on

 

[rayc]

With the enging off the Fridge internal light is working (so I assume that the fridge unit is also!)and all habitation lighting works including CAMOS. I swopped two relays over in the engine bay close to starter battery - this didn't make a difference.

AS everything 12v in the habitation area appears to work when the engine is off, I assume that the fuses to them are ok- so my problem appears to be down to engine start up stopping supply to the items not working

habitation 12v circuit
Step retraction
Reversing light activation
power to 2 reversing cameras


What next can I check out?

Thanks for reading and your interest/help

For the last 15 years or so UK built motor homes are designed so that the habitation 12v electrics are isolated when the engine is started. At the same time the alternator will power the 12v element of the fridge and charge the habitation battery. This is the same for caravans.
Therefore your fridge internal lamp will only work whilst that engine is off but it will keep items cold whilst you are travelling. It therefore appears you only have 3 problems i.e:
Step retraction: Could be a number of reasons. There will be a relay that is switched via the D+ signal from the alternator. This signal also controls the fridge 12v element and habitation battery charging which are the two relays you mention.
Reverse light activation: Possibly faulty reversing switch on gearbox - a common fault.
Power to reversing cameras. possibly the same reason the reversing light does not work.

 

[Crossingkeeper]

I have just remembered, through once nearly purchasing a Roadstar, that the reversing lights are mounted in the side skirts; is this the case in your van?

If so these will have been wired up by Lunar and connected to the original wiring loom rather than OE in the rear clusters.

With hindsight of many frustrating electrical investigations I have concluded that the more puzzling a fault is, the simpler the cause will be, however the black art is in tracking down the fault.

In your case I suspect the cause will be a dodgy connection or a faulty earth rather than a failed component or fuse but a wiring diagram and meter will be needed to trace where the problem is.

 

[dmf]

Yes, my Roadstar 630 has side skirt reversing lamps. I will check out secondary ignition fuse and use a meter if that isn't where the probelm is.

Will let you know how I get on - but snowing heavy here in Dover so unsure if I will be able to get over to Folkestone Storage today.

Thanks

 

[dmf]

Thanks for that info - can you tell me / point me to where the reversing switch can be located - and is it possible to determine if its faulty using a meter?

 

[rayc]

Thanks for that info - can you tell me / point me to where the reversing switch can be located - and is it possible to determine if its faulty using a meter?

https://www.fiatforum.com/ducato/151616-ducato-2-8jtd-reverse-light-switch.html

To check it take the connector off and short the wires together. This will simulate the switch operating and check the rest of the circuit.

 

[mike.T]

Hi dmf
This may not be of any use to you with your problem . But

I had the same type of thing with a Elddis M/H a few years ago
mine turned out to be a problem with the two relays added by Elddis under the bonnet
worth a look that the wiring has not been disturbed at the base of the relays ( also worth changing relays process of elimination ) to find the fault .
Hope you sort it soon
Mike

 

[daisyted]

Hi.
recently had similar problems with my Autotrail m/h.
Step problem was found to be sticking relay housed behind fridge vents.
Step worked OK from inner switch but did not retract upon engine start-up.
If you can access area near to switch i guess you should find a relay in addition to under bonnet relays.
Mike