Headlights won't operate, Understanding headlight circuits and relays |
|
Porsche, and the Porsche crest are registered trademarks of Dr. Ing. h.c. F. Porsche AG.
This site is not affiliated with Porsche in any way. Its only purpose is to provide an online forum for car enthusiasts. All other trademarks are property of their respective owners. |
|
Headlights won't operate, Understanding headlight circuits and relays |
Prospectfarms |
Mar 10 2012, 01:28 PM
Post
#1
|
Member Group: Members Posts: 495 Joined: 7-March 11 From: Louisville, KY Member No.: 12,801 Region Association: Upper MidWest |
When I pulled the headlight switch all the way out last night my lights would not open, and did not illuminate. No pop-up, no light. Parking and brake lights operate.
Best way to test the headlight switch? I'd like know how to test the wiring "downstream of the switch too. What circuits are closed when the headlight switch is pulled all the way out? Asking 'cause I was also seeing an intermittent alternator light that makes me think "voltage drop" at some connection and because I don't fully understand how the headlight switch acts on all the relays. As I understand it, the relays at the bucket assemblies activate their respective motors and the high-low relay responds to input from the switch in the steering column. Since the lights pop-up and illuminate when the switch is pulled, the dash switch must directly energize a pin on all three relays? |
Drums66 |
Mar 10 2012, 01:31 PM
Post
#2
|
914 Rudiments Group: Members Posts: 5,321 Joined: 15-January 03 From: Coronado,Cali Member No.: 151 Region Association: Southwest Region |
.....Grounding is very important! (IMG:style_emoticons/default/idea.gif)
(IMG:style_emoticons/default/bye1.gif) (IMG:style_emoticons/default/popcorn[1].gif) (IMG:style_emoticons/default/popcorn[1].gif) |
76-914 |
Mar 10 2012, 02:18 PM
Post
#3
|
Repeat Offender & Resident Subaru Antagonist Group: Members Posts: 13,509 Joined: 23-January 09 From: Temecula, CA Member No.: 9,964 Region Association: Southern California |
|
Prospectfarms |
Mar 10 2012, 02:54 PM
Post
#4
|
Member Group: Members Posts: 495 Joined: 7-March 11 From: Louisville, KY Member No.: 12,801 Region Association: Upper MidWest |
One of the wires to Fuse (1) is from the "downstream" leg of the high-beam indictor light on the tach. (Power to the indicator light is unfused. I assume it must pigtail off of the high beam lead from the high/low beam relay) Whatever the problem is with the headlights is making high-beam indicator light up when the parking lights are on.
Fuse 1 serves, or "goes to," the left high-beam. If the high-beam circuit can't close, perhaps the current at "the top" of fuse 1 reverses polarity and finds ground through the light. Does this help me isolate the problem? I can't figure out the rest of the diagram well enough to know. |
Prospectfarms |
Mar 10 2012, 03:11 PM
Post
#5
|
Member Group: Members Posts: 495 Joined: 7-March 11 From: Louisville, KY Member No.: 12,801 Region Association: Upper MidWest |
thanks, 76-914, now I'll know how to fix the switch if that's the problem.
OMT, no fog lights/relay on this car. |
tadink |
Mar 10 2012, 03:58 PM
Post
#6
|
Member Group: Members Posts: 379 Joined: 28-December 09 From: Napa Member No.: 11,181 Region Association: Northern California |
I expect that you have already assured that you did not knock the fuse out with your knee, and that the fuses are in fact all good? sorry to ask - just making sure! td
|
Prospectfarms |
Mar 10 2012, 06:18 PM
Post
#7
|
Member Group: Members Posts: 495 Joined: 7-March 11 From: Louisville, KY Member No.: 12,801 Region Association: Upper MidWest |
I expect that you have already assured that you did not knock the fuse out with your knee, and that the fuses are in fact all good? sorry to ask - just making sure! td Good call tadink. I had, in fact, knocked 10, 11, 12 out with my foot earlier that day and 12 may be the HL motors. but they've been checked, terminals cleaned and replaced. I went through all the fuses and they're seated and clean. I would like to know whether there is a single fuse that would knock out the whole headlight system. My interpretation of the wire diagram is no, but I'm not very good at reading it. |
ClayPerrine |
Mar 10 2012, 10:43 PM
Post
#8
|
Life's been good to me so far..... Group: Admin Posts: 15,521 Joined: 11-September 03 From: Hurst, TX. Member No.: 1,143 Region Association: NineFourteenerVille |
|
Prospectfarms |
Mar 10 2012, 11:10 PM
Post
#9
|
Member Group: Members Posts: 495 Joined: 7-March 11 From: Louisville, KY Member No.: 12,801 Region Association: Upper MidWest |
(IMG:style_emoticons/default/smilie_pokal.gif) (IMG:style_emoticons/default/pray.gif) (IMG:style_emoticons/default/smile.gif) Thank you so much, that was exactly what I was searching for. Great article too -- well done! Everyone should check it out.
BTW, my prob. was the switch, of course. |
Lo-Fi Version | Time is now: 10th June 2024 - 06:02 AM |
All rights reserved 914World.com © since 2002 |
914World.com is the fastest growing online 914 community! We have it all, classifieds, events, forums, vendors, parts, autocross, racing, technical articles, events calendar, newsletter, restoration, gallery, archives, history and more for your Porsche 914 ... |