Wiring Or Relays?

[neverarelayagain]

hi everyone,i have a problem that no garage seems to be able to fix,the horn,heater and reverse lights have stooped working(all stopped at the same time).all fuses have been checked and are ok but there is a clicking sound in the fuse box under the bonnet,similar to an indicator being used.would this be a wiring fault or relay fault,did get this error on last mot,,Offside Rear Direction indicator adversely affected by the operation of another lamp (1.4.A.2h).dont know if that would cause any other wiring faults.thanks all who take the time to look or comment.

Edited September 29, 2013 by neverarelayagain

[paul.h]

Welcome to the forum.

The MOT lighting problem could be something such as an earth wire fault (wire broken/rusty body connection) from the offside rear lamp or a bad bulb connection (corrosion in the bulb holder or on a bulb) or a dirty electrical connector to the lamp. I once had something similar on a car where a rear bulb dimmed as the indicators worked and I missed it before the MOT since I had not checked all the lights on together.

 

Similarly, the new problem could be an earth problem - check all the earth connections under the bonnet and if possible inside the cab. I am not familiar with the Relay but on our C5 there are earth connections at the sides of the front footwells. Are you sure all 3 stopped at the same time since in my case the horn is used only at MOT time, the reversing lights only noticed at night and the heater fan used quite a lot. If so, was there any preceding event or work being done on the van ? The clicking could be a relay - when does this sound, whilst trying the horn/reversing/trying the heater fan ?

[pikesrelaybus]

This does sound like a earth problem. Finding it can be tricky but not impossible. What are you like with a digital multimeter and soldering iron?. Personally, I'd look at the relastionship between these three things. It seems daft that the reverse lights, horn and heater have stopped working, hence a earth fault. Using your multimeter, or even a bulb with two long wires with croc clips on, Isolate each side of the circuit, ie check all the lives and then check all grounds, I wouldn't be afraid of taking off the footwell covers and have a jolly good nose about with a torch. I'd isolate which wire colours are commonly live and which ones commonly ground. Usually red and yellow for live wires, that's 12v, browns, blacks, ground etc. But best to look it up. If you find that say the rear cluster has no ground then try giving it a ground using a piece of wire with a 2 amp fuse in it, place a small bulb across the fuse. What your looking for is some kind of change, ie the reverse light comes on. If you make a mistake and short a positive to ground the fuse will blow and your lamp will light up but no more damage will be caused. If the relay clicks when you hit the horn then I'd say firstly, the relay is there to allow more current to the horn and seconly your fault lay's beyond the horn button which in effect works fine as the relay clicks.

 

What you really need is a circuit of these area, (Direction, horn, lights etc.). Citroen have these to hand and can print them off, whether they'll do you a favour and print a copy for you, who knows but I'm pretty convinced this is a earthing issue. With your bits of wire or multimeter you could confirm this. Basically, you need to elimitate possible causes until you come across the actual problem. One quick thought, if you had complete failure of these items and no intermittancy then your really looking for something that has totally failed, broken lug, caught wires, duff relay. I'm guessing that there could be potentially relays (solenoids) that feed different circuits. If you suspect a relay it's releativily easy to check it. Once checked, mark with tipex so that you have a indication that you've illiminated it. Testing relays, most have a circuit showing the coil and switch. Some relays have some circuitary in them which are slightly more difficult to test but I'd say that if this is a auxillary circuit type relay it'll be a simple one, use a battery, obviously, limit the current using a bulb in series, with the tails shorted the lamp will light, now try the tails (of the wires) across what you think is the coil and listen for a click. You might need to use a 10w bulb, that should be enough current flowing to make the relay click. Use your multimeter or another wire with bulb across the switch part. When you operate the relay this bulb should light. Seems really stupid with all these wires and bulbs but actually it's a pretty fool proof way of testing stuff, don't be tempted to just use a piece of wire for testing shorts, a mistake might be costly, the worse you can do with my silly idea's is light up a lamp bulb. Hope this helps..

[coastline taxis]

check youve got the right bulbs in the light cluster also have you got a aftermarket alarm or similar fitted