 Headlight bulbs-SOLVED!, How to test |
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| HalfMoon |
 Aug 1 2014, 09:48 PM
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#1
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Senior Member  Group: Members Posts: 828 Joined: 13-November 12 From: Shenandoah Junction, WV Member No.: 15,144 Region Association: MidAtlantic Region  |
Lost my right side headlight high beam. I have another headlight bulb lying around (from PO) but have no idea if it's good or not. Since it's a bit of a bith to change bulbs on our little 914's on a maybe, I thought I'd ask if anyone knows how to test a unmounted headlight bulb. I have an ohm meter and I also have a continuity tester.
Thanks in advance David |
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Replies(1 - 12)
| 914Sixer |
Aug 2 2014, 06:15 AM
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#2
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914 Guru Group: Members Posts: 8,897 Joined: 17-January 05 From: San Angelo Texas Member No.: 3,457 Region Association: Southwest Region 
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Check your fuses 1st, make sure it it seated properly. Replace with a NEW one just to be sure. I had one that looked good but it was not. I use a battery charger to check the lights and bulbs.
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| budk |
Aug 2 2014, 07:09 AM
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#3
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Yes! It's a Bumblebee! Group: Members Posts: 678 Joined: 24-July 10 From: Hickory, PA Member No.: 11,970 Region Association: MidAtlantic Region |
QUOTE(914Sixer @ Aug 2 2014, 08:15 AM)  Check your fuses 1st, make sure it it seated properly. Replace with a NEW one just to be sure. I had one that looked good but it was not. I use a battery charger to check the lights and bulbs. Or just use the battery in the car and 2 pieces of wire. |
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| Dtjaden |
Aug 2 2014, 08:51 AM
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#4
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Member Group: Members Posts: 232 Joined: 25-May 13 From: Morgan Hill, CA Member No.: 15,915 Region Association: Northern California |
Looking at the bulb from the back there are 3 connectors, left right and top. The left connector is the common and there should be continuity between that connector and the other two. The right connector is the low beam and the top connector is the high beam.
Using your ohm meter on a low scale you should get a value of just a a few ohms between the left connector and the right connector and between the left connector and the top connector. If you get no value between those connections the bulb is bad. |
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| HalfMoon |
Aug 4 2014, 01:53 PM
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#5
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Senior Member Group: Members Posts: 828 Joined: 13-November 12 From: Shenandoah Junction, WV Member No.: 15,144 Region Association: MidAtlantic Region |
QUOTE(Dtjaden @ Aug 2 2014, 10:51 AM) Looking at the bulb from the back there are 3 connectors, left right and top. The left connector is the common and there should be continuity between that connector and the other two. The right connector is the low beam and the top connector is the high beam. Using your ohm meter on a low scale you should get a value of just a a few ohms between the left connector and the right connector and between the left connector and the top connector. If you get no value between those connections the bulb is bad. Rats! I get continuity on the bulb that was in the car and my spare, and both (with my ohm meter set at 2k) give me values of .007. I reckon both bulbs are good and the next step is to test the socket with a test light (switched on with the headlight motor relay removed). I suspect a headlight switch :-( Thanks for the good test advice :-) |
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| HalfMoon |
Aug 4 2014, 02:06 PM
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#6
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Senior Member Group: Members Posts: 828 Joined: 13-November 12 From: Shenandoah Junction, WV Member No.: 15,144 Region Association: MidAtlantic Region |
QUOTE(HalfMoon @ Aug 4 2014, 03:53 PM) QUOTE(Dtjaden @ Aug 2 2014, 10:51 AM) Looking at the bulb from the back there are 3 connectors, left right and top. The left connector is the common and there should be continuity between that connector and the other two. The right connector is the low beam and the top connector is the high beam. Using your ohm meter on a low scale you should get a value of just a a few ohms between the left connector and the right connector and between the left connector and the top connector. If you get no value between those connections the bulb is bad. Rats! I get continuity on the bulb that was in the car and my spare, and both (with my ohm meter set at 2k) give me values of .007. I reckon both bulbs are good and the next step is to test the socket with a test light (switched on with the headlight motor relay removed). I suspect a headlight switch :-( Thanks for the good test advice :-) Poop. As I suspected the top connector won't light up a test light with the headlights switched on in the high position (motor relay out of course). Now I get to start looking at other stuff :-( |
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| HalfMoon |
Aug 4 2014, 02:20 PM
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#7
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Senior Member Group: Members Posts: 828 Joined: 13-November 12 From: Shenandoah Junction, WV Member No.: 15,144 Region Association: MidAtlantic Region |
QUOTE(HalfMoon @ Aug 4 2014, 04:06 PM) QUOTE(HalfMoon @ Aug 4 2014, 03:53 PM) QUOTE(Dtjaden @ Aug 2 2014, 10:51 AM) Looking at the bulb from the back there are 3 connectors, left right and top. The left connector is the common and there should be continuity between that connector and the other two. The right connector is the low beam and the top connector is the high beam. Using your ohm meter on a low scale you should get a value of just a a few ohms between the left connector and the right connector and between the left connector and the top connector. If you get no value between those connections the bulb is bad. Rats! I get continuity on the bulb that was in the car and my spare, and both (with my ohm meter set at 2k) give me values of .007. I reckon both bulbs are good and the next step is to test the socket with a test light (switched on with the headlight motor relay removed). I suspect a headlight switch :-( Thanks for the good test advice :-) Poop. As I suspected the top connector won't light up a test light with the headlights switched on in the high position (motor relay out of course). Now I get to start looking at other stuff :-( Demmit! Fuse is good. I wonder if a relay gone south could make the right side highbeam not work? Still suspecting the switch (IMG:style_emoticons/default/sad.gif) |
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| HalfMoon |
Aug 4 2014, 09:40 PM
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#8
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Senior Member Group: Members Posts: 828 Joined: 13-November 12 From: Shenandoah Junction, WV Member No.: 15,144 Region Association: MidAtlantic Region |
Durn and double durn!
I tried a spare switch, then a spare headlight relay, and also a spare flasher relay (my flashers stopped working too), now I suspect the turn signal column switch. |
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| Mike Bellis |
Aug 4 2014, 10:11 PM
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#9
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Resident Electrician Group: Members Posts: 8,345 Joined: 22-June 09 From: Midlothian TX Member No.: 10,496 Region Association: None 
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If one light works, it's not the switch or the Hi/Lo relay. Spin the fuse in the fuse holder . If the other lamp will light, there is power at one side of the fuse. The wire goes directly from the fuse to the lamp.
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| HalfMoon |
Aug 4 2014, 10:25 PM
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#10
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Senior Member Group: Members Posts: 828 Joined: 13-November 12 From: Shenandoah Junction, WV Member No.: 15,144 Region Association: MidAtlantic Region |
QUOTE(Mike Bellis @ Aug 5 2014, 12:11 AM) If one light works, it's not the switch or the Hi/Lo relay. Spin the fuse in the fuse holder . If the other lamp will light, there is power at one side of the fuse. The wire goes directly from the fuse to the lamp. Mike, you win the prize tonight! Indeed that worked. However my flashers still aren't working (IMG:style_emoticons/default/sad.gif) I've had my turn signal switch out lately (wiper switch woes) and that coincided with the flasher loss (evidently the right side higbeam was merely a coincendetial and un related problem). I've tried a new flasher relay and even swapped out a known to be good hazard switch....I still wonder at the column turn signal switch in reference to the loss of hazards. Are they or can they be related? |
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| Mike Bellis |
Aug 4 2014, 10:28 PM
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#11
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Resident Electrician Group: Members Posts: 8,345 Joined: 22-June 09 From: Midlothian TX Member No.: 10,496 Region Association: None
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QUOTE(HalfMoon @ Aug 4 2014, 09:25 PM) QUOTE(Mike Bellis @ Aug 5 2014, 12:11 AM) If one light works, it's not the switch or the Hi/Lo relay. Spin the fuse in the fuse holder . If the other lamp will light, there is power at one side of the fuse. The wire goes directly from the fuse to the lamp. Mike, you win the prize tonight! Indeed that worked. However my flashers still aren't working (IMG:style_emoticons/default/sad.gif) I've had my turn signal switch out lately (wiper switch woes) and that coincided with the flasher loss (evidently the right side higbeam was merely a coincendetial and un related problem). I've tried a new flasher relay and even swapped out a known to be good hazard switch....I still wonder at the column turn signal switch in reference to the loss of hazards. Are they or can they be related? Yes. |
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| HalfMoon |
Aug 4 2014, 11:07 PM
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#12
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Senior Member Group: Members Posts: 828 Joined: 13-November 12 From: Shenandoah Junction, WV Member No.: 15,144 Region Association: MidAtlantic Region |
QUOTE(Mike Bellis @ Aug 5 2014, 12:28 AM) QUOTE(HalfMoon @ Aug 4 2014, 09:25 PM) QUOTE(Mike Bellis @ Aug 5 2014, 12:11 AM) If one light works, it's not the switch or the Hi/Lo relay. Spin the fuse in the fuse holder . If the other lamp will light, there is power at one side of the fuse. The wire goes directly from the fuse to the lamp. Mike, you win the prize tonight! Indeed that worked. However my flashers still aren't working (IMG:style_emoticons/default/sad.gif) I've had my turn signal switch out lately (wiper switch woes) and that coincided with the flasher loss (evidently the right side higbeam was merely a coincendetial and un related problem). I've tried a new flasher relay and even swapped out a known to be good hazard switch....I still wonder at the column turn signal switch in reference to the loss of hazards. Are they or can they be related? Yes. Fairly confident my spare turn signal switch is good so I'll pull the old switch in the morning and test it. I'm certain I'll find that switch to be bad. Hopefully my spare will retunr the hazards (IMG:style_emoticons/default/biggrin.gif) |
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| HalfMoon |
Aug 6 2014, 02:21 PM
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#13
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Senior Member Group: Members Posts: 828 Joined: 13-November 12 From: Shenandoah Junction, WV Member No.: 15,144 Region Association: MidAtlantic Region |
Mike had it right!
Good on ya mate (IMG:style_emoticons/default/biggrin.gif) Dressing the fuse worked. |
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