The other day I bought a 1997 Nissan Primera. The battery was dead when I bought it. Today, I replaced the battery. Now everything works fine acxept for the tail lights which don't come on when the headlight switch is turned on. The tail light bulbs are perfectly OK (all filaments light up when fed with 12 volts). I also checked the two tail light fuses. Neither of them is blown. So the fault must be somewhere else. Anyone suggest where it might logically be?
Many thanks
RickyC
Weird having two tail light fuses.
Have you checked the inputs to the fuses?
Do other lights on the rear clusters work - this should prove the returns (grounds)
Does it have parking lights where the indicator switch selects right or left sidelights with the ignition switched off?
A fuse is blown or an earth fault at the back of the car.
No logic here, but every time I've had a wacky fault like that it's turned out to be a bad earth. Look for a black cable with a rusty terminal.
HTH
On Tue, 15 Feb 2005 22:31:26 GMT, snipped-for-privacy@SurfinSouthCoast.com (RickyC) strung together this:
More than likely a dodgy earth. Best bet is get a meter out and see where the pos\neg go\don't go. No need for guessing then.
I'm not too savvy on electronics, but I'm thinking that I'd need an ohm meter with very long wires, so I can clip one on the battery and prod the other end at various points between it and the tail lights, yes?
RickyC
No, but will try and check that tomorrow. If I can figure out which side of the two fuses are the input.
Thanks for your help. Yes, the brake lights (second filament in the same tail light bulbs) work fine. So do the indicators (the only other bulbs back there).
I'm not sure. Why do you ask?
RickyC
Voltmeter, and sharp pin to pierce insulation. Cahiis is always 0v - lights should be at +12v.
MAY be a relay in there or somne weiord switch - do the bulbs come on with sidelights/parking lights?
Pull the fuse out... the side with 12V is the input. If neither side has
12V then that is your problem!(I found the side lights did not work on my car after I bought it, checked the fuse and found no feed to it. In the end found there was supposed to be a small plug in relay on the same panel as the fuse (located above the drivers footwell) which some bright spark had vacuumed off when valeting the car prior to selling it!)
If you are going to do it on an ohms range then make sure you disconnect the live from the battery... otherwise the first one you prod will probably cost you a new meter! A volts range will tell you which bits are live, so if you find you can trace 12V as far as the bulb then you know it must be the earth.
Two fuses ? Both circuits failed ? Start looking at the common factor; the switch.
Is there a parking switch ? Can fiddling with that make them come on ?
Get your test lamp out (buy one if you don't have one - Blackspur do a quite decent one for a couple of quid). Test for voltage on the bulbholder contact, with the bulbs out. Test the output of the light switch.
Turn the indicators or hazards on, then have an assistant press the brake pedal. Do the stop lights come on as expected, or do they cause problems with the indicators ? If so, then it's time to look for earth faults on the light cluster. (Having a Ford badge is usually an indication of these)
Do _NOT_ use a meter to test car electrics. They'll still register 12V OK even through a poor connection, but it can't deliver enough current to work properly (I once wasted three days unnecessarily eviscerating a Citroen XM dashboard by having done just that ! )
You'll be wanting a Haynes too, for the wiring diagram colour codes, if nothing else.
Are they the right bulbs ? Are they combined tail light and stop bulbs, or separate ? If it's a fitting for a combined bulb, then there are options for getting the wrong bulbs in there.
Two fuses - one each side, pretty common on non-Brit vehicles for the last few decades.
One good place to check is around the rear seat. The wiring loom to the rear of the car passes through here somewhere and it's often chafed by the seat, parcel shelf, spare wheel or some other big heavy lump in the back. There may also be a multi-way connector around here, which will be a good place to do some more testing and isolate the fault to forwards or behind it.
When you need electrical bits to fix it, Vehicle Wiring Products (on the web) do excellent mail order. Car electrics are much easier than they're made out to be and very few pieces are maker-specific.
"Andy Dingley" wrote
I recently had one tail light out (on an old Merc 230E) and it was the headlamp switch at fault.
chassis :-)
I like the pin tip - thanks.
No switches that I am aware of have any effect on the tail lights. The tail lights (and them alone) do not come on whatever I do. The brake lights (which are another filament in the same bulb) work fine.
PS Thanks to everyone for the suggestions. I'll go through the wiring this weekend until I locate the fault.
RickyC
headlight
logically be?
Hmm, if you're not too savvy, once you've checked the fuse, the bulb and for any obvious dodgy connections, might be easier to send to an auto electrician.
I'm and electrical and electronics engineer by trade, and I threw the towel in on an intermittent fault to earth, blowing the tail light fuse on my Frontera.
The electrician had to strip out half the dashboard to narrow down the fault, which turned out to be where insulation had chafed off over a bulkhead.
So saved me a days scrabbling about underneath the car dashboard skinning my knuckles and trapping my fingers.
I think it was about =A370, but well worth it :-)
Rgds
Paul.
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