Stumped by 'simple' auto-electrical issue

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bastardsquad, Jan 26, 5:54am
OK.so the GF wants some 'audi lookalike' LED lights on her 2003 Cefiro(AKA maxima).so I put some self adhesive Jaycar jobbies on the front below the driving lights and power them by piggybacking to the small parklight bulb in the main headlight assembly - switch lights on and the LED strip lights work. Did a reasonable installation, heatshrinked the connections after soldering and took my time thinking it was weathertight. All was well for a month or so, and in the recent downpour, one of the strips has gone bang(probably due to moisture ingress) when the lights were switched on.Now comes the problem.

Normal headlights work, but parklight,'spotlight/drivi-
ng light' and rear lights dont work when lights are switched on. I checked the main engine bay fuses, all intact. I checked the drivers kick panel fuses, again all intact. I checked the park light bulbs(easily accessible) and both have not blown. I havent checked the spotlight bulbs, but if either was blown, it wouldnt stop the rest of the lights working - ditto the rear lights. I have opened and looked at the relays for the lights etc and no blackening or burnt smell. I havent swapped the relays for the 'non main headlight' lights yet.is this worth it!

I have exhausted my elec knowledge at this point and i'm surprised that a short/burnout at a 'bulb' point didnt pop the primary fuse, yet has taken out all the 'non main headlight' lights !Any suggestions from the knowledgeable ones! (apart from avoid Jaycar cheapie stick-ons lol)

phillip.weston, Jan 26, 5:56am
the park lights and tail lights are on the same circuit, I would say you have blown a fuse or a relay.

bastardsquad, Jan 26, 6:05am
Pretty much what I thought, I checked ALL the fuses and all are intact. If i swap the headlight relays(working) for the park/tail relays and STILL get no joy.then what do you think it could be!

falcon15, Jan 26, 6:23am
Hve you checked the fuse with a multimeter or just looked at it. sometimes they look ok when they are actually blown

robertsons-nes, Jan 26, 6:44am
have you checked the actual headlight switch itself

carkitter, Jan 26, 7:05am
I would start looking for voltage at this point now a visual inspection (the first place to start) has turned up blank. Start at the fuse box inside the car and check for voltage on either side of the fuse. Test the relays the park light switch, and the individual bulbs.

dent, Jan 26, 7:10am
I would be double checking the fuses even swapping in a fuse knowen too be in good condition. Or remove fuse and put a current meter across fuse holder.

jono2912, Jan 26, 7:48am
Spot on.

bastardsquad, Jan 26, 8:25am
So it's out with the multimeter looking for 12vDC across the fuse/relay terminals then! Whilst i realise fuses can blow'inconspicuously',-
I'm very confident theyre OK after a thorough visual inspection of each and every one in bright daylight today. I'll have a poke around checking voltages at each of the suspect places : (lights fuses and relays) and see. Cant see what good running meter across wires at bulb end will do when bulbs are OK!(ie: if bulbs are good, fault must be prior to them).

Edit: if there is no voltage at fuse terminals with lights switched on, does this mean fault is likely to be relay!

girlracer2005, Jan 26, 8:40am
bulbs dont always turn black when they blow but i would check for voltage in the places said

jono2912, Jan 26, 8:43am
Yeah yeah, it took you 10 minutes to come up with that one.

Test the fuse voltage with the fuse still in (on a blade fuse there is 2 metal contact points on the top) if you can and on the neg side, that way you can find out 2 things. If the fuse is burnt out, and if there is power. Does that make sense! Also sensible to change the relay with another as a quick method of testing.

jono2912, Jan 26, 8:45am
Likely story.

jono2912, Jan 26, 8:55am
Indeed, I would.

bastardsquad, Jan 26, 9:06am
No resistance per se : ) I'm just operating at the limits of my auto sparky kung fu here, so i'm fishing for info/tips before I admit defeat and pay soeone else to diagnose a seemingly simple fault !

vingina, Jan 26, 9:14am
possible if no voltage at the base of fuse before the load, eg take fuse out turn lights on etc, if no voltge at start of fuse then possible you have burnt out a wire. Sometimes a increase in current although minimal with leds can cause a already weak wire to burn out. it may be a case of a coincidence and maybe water has traked down a cable etc etc.

easygoer, Jan 26, 9:14am
The general rule for testing electrical circuits is to start at the point of supply testing for voltage and follow the circuit to the end

leighfrancesca, Jan 26, 9:26am
+1

If you have a multimeter remove the kick panel fuse for that lighting circuit and check for 12VDC.While the fuse is out carry out a resistance check on it to confirm that it is indeed serviceable - a good reading should be somewhere in the vicinity of 0 - 0.4 ohms, if it reads overload or something to that effect replace it.

Because it sounds like you've lost the whole circuit ie none of the lights on that circuit are working you may have burnt out a common wire to all of them or there is still a blown fuse somewhere that you haven't found yet.

Good luck

bigfatmat1, Jan 26, 9:32am
out of all these posts I find #6 & #5 the only ones I can understand. Whats going on all these people helping and his park lights still don't go. Do fuses have a neg side jono! wtf why would you use a multimeter is this to confuse yourself even more.

op use a test light with a bulb not a led or a multimeter.
Recheck all fuses with your test light check them in place. check the ones under the bonnet and inside the car. Then look into where the fuses go and make sure you have not put any back in the in correct places. If you are positive you have checked them and they are all ok. move onto the switch listen for a relay click no click access the switch loom connector and back probe with ya test light while flicking between park and off to test the switch if there is a click locate relay and test. if there is a night park switch in the circuit make sure this is plugged in. a while since I worked on a cefiro but I am pretty sure this will be positvely switched via the column switch no relay and possibly through a bcm good luck

jono2912, Jan 26, 10:02am
Nevermind, I can't explain things well, via text. I didn't think it would make sense.

leighfrancesca, Jan 27, 10:05am
Mate, I see you live in Waitakere too.I could probably spare an hour of my time over a weekend or something if you wanted someone to have a look at it with electrical experience.

carkitter, Jan 27, 10:48am
The most likely point of failure is the fuse in the fuse box under the dash. Put the -ve terminal of your multimeter to earth, and test the voltage on both sides of the fuse with the +ve terminal. Voltage on both side means that the fuse is okay AND that the main fuse under the bonnet is okay. Voltage on one side only means the fuse your testing is blown. No voltage at all means you need to test the main fuse under the bonnet. Use this technique all the way to the individual bulbs which live at the end of the circuit until you find where the voltage is missing, then search back until you pinpoint the problem.

In the unlikely but possible event that you find voltage is okay, then you may have a faulty earth. Switch your multimeter to Ohms (resistance) and test the earth points of the switch and relays. You should see 0.0 for a good earth, 1 for a bad earth. Look for corrosion on any earth wires or screws. A faulty earth is more likely bad luck than bad workmanship.

lugee, Jan 27, 10:59am
Have you removed/disconnected your LED mods! Its possible that one of them has gone short circuit and pulling enough current to cut the lights (electrons follow the path of least resistance), but not enough current to blow a fuse.

jono2912, Jan 27, 10:59am
That is what I meant.

mellisa2000, Jan 27, 11:05am
Agree with the larger unskinny floor rug.
Sorry, can't offend due to rules.

carkitter, Jan 27, 11:11am
Test light is fine for testing the presence of voltage but ain't much good for testing earths. I tend to use them only for testing fuses not circuits, though it's personal preference I guess.