Motorhome Facts Forum banner
1 - 12 of 12 Posts

·
Registered
Joined
·
144 Posts
Discussion Starter · #1 ·
Hi.

I've an electrical fault with my reverse light and someone has suggested that it may be an issue with the actual switch but I'm slightly dim and don't know what the switch will look like, where to find it or how to access it to test! Can anyone please advise?

I've got 12V at the holder (With NO bulb in & reverse selected) but as soon as I add a bulb, the voltage drops to 0V. All earths & connectors seem like new.

Thanks for any help
 

·
Premium Member
Joined
·
7,970 Posts
Before going to the trouble of getting at the switch it would be better to check at the bulb holder to determine whether the problem is the positive or negative side of the bulb. I know that you have said that the voltage is present across the terminals without the bulb but it drops to 0v with the bulb inserted. This means that there is a high resistance [bad connection or similar] in EITHER/BOTH the positive feed to the lamp or the negative which is connected through to the bulb via the reversing ligh switch.
I would start by running a bit of wire from the chassis to the NEGATIVE side of the bulb and hopefully the lamp will light meaning the high resistance is in the circuit from the reversing light switch. If it doesn't light with the negative strap then take a good positive feed to the bulb and hopefully it will light showing that the high resistance is in the positive feed.
I suspect that a auto electrician would sort this in 10 minutes so if your tests do not help then I suggest a mobile auto electrician is called.
 

·
Registered
Joined
·
144 Posts
Discussion Starter · #3 ·
rayc said:
Before going to the trouble of getting at the switch it would be better to check at the bulb holder to determine whether the problem is the positive or negative side of the bulb. I know that you have said that the voltage is present across the terminals without the bulb but it drops to 0v with the bulb inserted. This means that there is a high resistance [bad connection or similar] in EITHER/BOTH the positive feed to the lamp or the negative which is connected through to the bulb via the reversing ligh switch.
I would start by running a bit of wire from the chassis to the NEGATIVE side of the bulb and hopefully the lamp will light meaning the high resistance is in the circuit from the reversing light switch. If it doesn't light with the negative strap then take a good positive feed to the bulb and hopefully it will light showing that the high resistance is in the positive feed.
I suspect that a auto electrician would sort this in 10 minutes so if your tests do not help then I suggest a mobile auto electrician is called.
thanks for your suggestion. Though I'm not totally sure what the results would mean?

The NEG is common to all the bulbs in the cluster and all the other bulbs show 12V and work just fine, though I will try adding a new temporary -VE

I'll try connecting the tail light's +ve to the reverse light holder too but when i find out which one is the "Problem" wire, what do I do then?

I guess I've got to access the switch?

Can you enlighten me any further as to just how to interpret the results and how to sort please? Or where the switch is located etc.

Thanks
 

·
Premium Member
Joined
·
7,970 Posts
IF the negatives are common then the reversing light switch must be swithching the positive supply to the bulb. In that case you can discount a problem with the negative feed. An easy check would be to switch the sidelights on and with a piece of wire bridge the positive of the side light to the positive of the reversing light. The bulb should light.
If it does then the problem will be the positive supply to the reversing light switch, the switch itself or the connection from the switch to the lamp.
 

·
Registered
Joined
·
144 Posts
Discussion Starter · #5 ·
rayc said:
IF the negatives are common then the reversing light switch must be swithching the positive supply to the bulb. In that case you can discount a problem with the negative feed. An easy check would be to switch the sidelights on and with a piece of wire bridge the positive of the side light to the positive of the reversing light. The bulb should light.
If it does then the problem will be the positive supply to the reversing light switch, the switch itself or the connection from the switch to the lamp.
That's what I thought and was lead to believe but I still am no wiser, though thanks for your suggestions, as to where the reversing light switth is located and how to access it.

Anyone know please?
 

·
Registered
Joined
·
144 Posts
Discussion Starter · #6 ·
rayc said:
IF the negatives are common then the reversing light switch must be swithching the positive supply to the bulb. In that case you can discount a problem with the negative feed. An easy check would be to switch the sidelights on and with a piece of wire bridge the positive of the side light to the positive of the reversing light. The bulb should light.
If it does then the problem will be the positive supply to the reversing light switch, the switch itself or the connection from the switch to the lamp.
you're right, the +VE from the side light makes the reverse light bulb light up.

Now I need to locate the reverse light switch - does any one know where it is please?

anyone???????
 

·
Registered
Joined
·
14,156 Posts
You will need to give your exact make and model number for a definitive answer for example on a 2006 Ducato 2.8jtd it is grey in colour and on top of the gearbox but hidden by an air pipe and clutch mechanism (from Fiat forun)
 

·
Registered
Joined
·
144 Posts
Discussion Starter · #11 ·
rayc said:
www.motorhomefacts.com/ftopic-61087.htm

hope it helps
Thanks but IE comes up with "The page does not exist"

I don't know if that topic told me where to find the reverse switch etc, as per my original question but I've had the answer from another forum.

Found the switch and diagnosed the issue

thanks for all your help everyone
 

·
Registered
Joined
·
1 Posts
Hi , just spent TWO HOURS changing my reversing switch. I dont think it would have been possible without putting the van up on full scale garage lifts ,courtesy of my friend Noddy at Donson Motorhomes in Harpenden, who lent me the use of his ramps for my 05 2.3 Fiat Tracker .Complete pig of a job even then .Half an hour to get the plug of the top and another one and a half to get the switch out .We needed to snap the plastic top of the switch to get a socket on it and even then it is a three handed job .I would not recommend trying this one one your drive !!!! Another Fiat known problem I presume .Only 11000 miles on the clock .My last Autotrail only had 30,000 on the clock when the dreaded Fifth gear packed up in Switzerland( it's a long drive home in Fourth !! )
 
1 - 12 of 12 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top