w124 indicator fuse blows

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Dave Lewis

Active Member
Joined
Nov 7, 2003
Messages
725
Location
Bristol
Car
'06 Subaru Forester 2.5XT, '98 Subaru Forester
Hi, my E280 developed a fault last night, and I would appreciate some advice: when indicating left, the fuse (no.6) blows. There's no problem when indicating right. If I switch the hazards on, it blows both fuse no.6 and no.9. When operating the infra red alarm/immobiliser/central locking, the indicators do not flash like they should, but neither do the fuses blow. I've checked the bulb holders front and rear, no obvious shorts. I've tried indicating left with the bulbs removed, fuse no.6 still blows. Is it possible that the relay is faulty? I need a quick fix, as everything is closing down today for the christmas break, and I need the car on Sunday for an important job. Bah!
 
The relay is fine, this must be a wiring or stalk fault as all the rest of the system used is common to both sides.

The alarm possibly has seperate fuses for the indicators so a thief can't disable the alarm by shorting out the indicator bulb.
 
Thanks DM. I think it must be a wiring fault as the stalk works perfectly for all it's other functions. I'll investigate. Or try and remember to only signal right. Pity it's not a BMW - no indicators wouldn't be a problem :(
 
what happens if you unplug the indicator bulb holders rather than just taking the bulbs out ?

You could also try disconnecting the loom section which feeds the clusters - that way gives you half a chance of isolating the fault

Have a look at the rear cluster - we had all sorts of problems with our old 230 estate that centred around the passenger side rear lights.

Is the alarm linked into the main engine loom and is it possible there is a short there?
 
what happens if you unplug the indicator bulb holders rather than just taking the bulbs out ?

You could also try disconnecting the loom section which feeds the clusters - that way gives you half a chance of isolating the fault

Have a look at the rear cluster - we had all sorts of problems with our old 230 estate that centred around the passenger side rear lights.

Is the alarm linked into the main engine loom and is it possible there is a short there?

Thanks for your help Andy. I've unplugged the rear and front clusters, and isolated the towbar electrics. I've inspected the relevant bits of loom, and any extra fuses. No dice. The engine loom was replaced with new last March. The alarm system is the factory infra-red, option code 880. I'll keep poking around.
Oh, and Yuletide greetings to you and yours.
 
This from the E class owners bible:- [fuse 6 is 8amp fuse 7 is 16amp by the way:( ] so you could maybe see a problem here. However if the problem hasn't appeared before seems a bit of a long shot??? fuse 6 is allocated to the indicators pre 93 but I can't find a fuse allocation at all for the indicators post 93.:confused: The other possibility is the alarm system control unit has blown up big time and is allowing a " back path " to earth via the indicator triggering lines. If you can disconnect the alarm unit temporarily to test this theory - (think there will be a main plug with most of the lines out) that would rule it out.
 

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Thanks for taking the time to dig that out Graeme. There's not been a problem with this before, and what seems to happen is the relay clicks in a muted way a couple of times before the fuse blows, without either of the nearside front or rear indicators showing any signs of life. The offside indicators work as normal. I'm beginning to suspect the immobiliser/alarm system. When operated, none of the indicators flash as they should.
 
Thanks for your help Andy. I've unplugged the rear and front clusters, and isolated the towbar electrics. I've inspected the relevant bits of loom, and any extra fuses. No dice. The engine loom was replaced with new last March. The alarm system is the factory infra-red, option code 880. I'll keep poking around.
Oh, and Yuletide greetings to you and yours.

Thanks Dave,

I'm tempted to agree with you about the alarm then - can you disconnect that?.
 
Surely the alarm would affect both sides. I suspect a wiring fault or even the stalk.
 
I'll have a go tomorrow. After I've cooked the turkey.
 

Precisely, my last resort. Great fun when changing lanes on the motorway :D
Do people actually know what these signals mean nowadays, particularly the left turn signal? It could cause untold strife if wrongly interpreted as a particularly extravagant rude gesture...
I had to use hand signals in my first mini, as nothing worked on it. Slowing down and turning involved pumping the brakes 3 times, windmilling the wrist out the window, holding the elastic wand gearstick in gear, and somehow finding extra limbs to operate the steering.....
 
Surely the alarm would affect both sides. I suspect a wiring fault or even the stalk.

Most alarms of that vintage have 2 separate leads for RH and LH (usually black/red) scotch-locked into the 2 front indicator lines from the alarm unit. Whether this would mean discrete circuitry in the alarm unit I don't know? As Dieselman said sometimes these are fused to stop the alarm being disabled by breaking the sidelights. Some are--- some aren't. What is certain is that the fuse 6 ( 8 amp) is being subjected to a high current draw when asked to supply the left hand indicators. This is almost certainly a short to earth somewhere-where---- well that's the $64k question.:confused:
 
Still no luck tracing this fault. I found a 10amp fuse in the passenger foot well in with the alarm gubbins. This blows as soon as the keyfob is operated, ie when the indicators should flash. The fuses also blow when the hazards are switched on. This leads me to rule out the stalk. I've also checked the side indicator repeaters. Trouble is I can only do a visual inspection, looking for obvious breaks and kinks. The alarm system appears to be an after market fitment, and not very tidily done. I'll have to give up, and hope I can find an auto electrician open tomorrow :(
 
Still no luck tracing this fault. I found a 10amp fuse in the passenger foot well in with the alarm gubbins. This blows as soon as the keyfob is operated, ie when the indicators should flash. The fuses also blow when the hazards are switched on. This leads me to rule out the stalk. I've also checked the side indicator repeaters. Trouble is I can only do a visual inspection, looking for obvious breaks and kinks. The alarm system appears to be an after market fitment, and not very tidily done. I'll have to give up, and hope I can find an auto electrician open tomorrow :(

Have a look at the multi relay in the fuse box.
 
Buy a cheap multimeter or continuity tester from maplin, Halfords or similar. You can get one for £5.

Another test would be to wire a bulb up as a continuity tester and connect one side to 12v and the other to the indicator wiring after the indicator relay/stalk/fuse.
An indicator bulb holder or alarm output fuse should do for this test.

If the bulb lights you have a short to Gnd which you can find by disconnecting parts of the loom until it goes out.
 
Thanks Nick, I had a look at that first off, all I could do was a visual inspection - not much use. When indicating left, the relay makes a muted clicking sound (like it does when a bulb is out) a couple of times, then the fuse blows, so I'm thinking it's downstream of the relay. Electrics are not my forte, so I'm literally in the dark on this.
 
Thanks Nick, I had a look at that first off, all I could do was a visual inspection - not much use. When indicating left, the relay makes a muted clicking sound (like it does when a bulb is out) a couple of times, then the fuse blows, so I'm thinking it's downstream of the relay. Electrics are not my forte, so I'm literally in the dark on this.

Pop the top of the relay and see if there's any thing obvious.
 
The other things driven off that combination relay H are the heated rear screen and the wipers- are they still working OK?
 
Everything else on that relay works fine Graeme. (I tried to get one locally on wednesday for substitution, but no stock). I popped the top off too, but there was nothing visually amiss.
I still suspect the alarm system, since it's the only exposed bit of wiring apart from the tow bar electrics (now disconnected), and has not been routed very well. The other thought I had was moisture/corrosion in the fusebox and relay compartment, but it's all bone dry and looks like it was made yesterday. I think I've gone as far as I can with my limited knowledge and lack of time. I have to get myself plus 2 other band members plus gear to the midlands in the early hours of Sunday morning, dump the car, and change over to our tour bus (OK, camper van ;) ) en route to Scotland for a short tour. I'll just have to do it without signalling left :eek: and get it sorted when I get back.
Thanks for the help chaps. Much appreciated.
 

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