 Fuse 9 Blows when Ignition Turned to "On", SOLVED! |
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| poorsche914 |
 May 3 2015, 05:34 PM
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#1
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T4 Supercharged  Group: Members Posts: 3,089 Joined: 28-May 09 From: Smoky Mountains Member No.: 10,419 Region Association: South East States  |
I have done a search and found a couple other threads with a similar situation but any remedy listed did not work for me.
As stated in title, Fuse #9 blows within seconds of turning ignition switch to the ON position. Strange thing is, it has been somewhat intermittent. Fuse blew a couple weeks ago. Replaced it and drove for a week and then it blew again. Replaced it and it lasted about maybe a day. Now, every time the key is turned to ON the fuse blows. Here are some things I have tried in hopes of isolating the source of the problem: Removed POS lead from battery to starter - blows Could it be the ignition switch? The car still starts and runs fine except the following items do not work: fuel gauge Wipers and fresh air fan work. And, in case it matters... '74 2.0 D-jet Thanks! (IMG:style_emoticons/default/driving.gif) |
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| Mike Bellis |
May 3 2015, 10:29 PM
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#2
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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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Check the brake light switch under the pedal board. The hot lead can come loose and arc/short to ground, blowing the fuse.
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| etcmss |
May 4 2015, 04:36 AM
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#3
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etcmss Group: Members Posts: 183 Joined: 20-April 06 From: Lancaster, Ky Member No.: 5,899 Region Association: Upper MidWest |
I had something similar and it was a bad bulb in the instruments.
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| Tbrown4x4 |
May 4 2015, 05:50 AM
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#4
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Senior Member Group: Members Posts: 703 Joined: 13-May 14 From: Port Orchard, WA Member No.: 17,338 Region Association: None
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Wow. That fuse powers a lot of stuff. I agree with Mike, the brake light switch is a good place to start, and can isolate a few things.
One of my tricks to avoid blowing fuse after fuse, is to wire a sealed beam headlight in place of the fuse. There is enough load to keep the circuit live without damage, and when the short is gone, the light goes out. Very helpful when moving harnesses around looking for intermittent shorts. |
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| rhodyguy |
May 4 2015, 07:46 AM
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#5
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Chimp Sanctuary NW. Check it out. Group: Members Posts: 22,079 Joined: 2-March 03 From: Orion's Bell. The BELL! Member No.: 378 Region Association: Galt's Gulch |
Have you had the rear bumper off lately? Even if you haven't check the leads for the plate lights. Specificly where they pass thru rear panel.
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| Dave_Darling |
May 4 2015, 08:49 AM
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#6
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914 Idiot Group: Members Posts: 14,984 Joined: 9-January 03 From: Silicon Valley / Kailua-Kona Member No.: 121 Region Association: Northern California
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Just gonna suggest the license plate lights! I got the leads reversed on one of them once, and couldn't figure out why the fuse kept popping...
--DD |
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| Mike Bellis |
May 4 2015, 09:38 AM
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#7
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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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Another trick:
use a test light in place of the fuse. It will light up while the problem is shorted to ground and go out as soon as you clear the problem. Just connect the test light to each side of the fuse holder. |
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| poorsche914 |
May 4 2015, 11:04 AM
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#8
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T4 Supercharged Group: Members Posts: 3,089 Joined: 28-May 09 From: Smoky Mountains Member No.: 10,419 Region Association: South East States |
Thanks for all the responses. I like the idea of hooking up a test light. (IMG:style_emoticons/default/smile.gif)
My rear plate light is not connected - wires are taped. Will check the brake light switch this evening. I swapped out the ignition switch and relay board - no difference. I noticed on the wires to the ignition switch that two wires - one black, one red - going to the same connection have an ever-so-slight melted look to the black casing. Going to try to trace that. I hate electrical issues (IMG:style_emoticons/default/dry.gif) (IMG:style_emoticons/default/driving.gif) |
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| SirAndy |
May 4 2015, 11:15 AM
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#9
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Resident German Group: Admin Posts: 41,633 Joined: 21-January 03 From: Oakland, Kalifornia Member No.: 179 Region Association: Northern California |
QUOTE(poorsche914 @ May 4 2015, 10:04 AM)  My rear plate light is not connected - wires are taped. I'd check that tape just to be sure. Not sure if it's on the same fuse, but the heater light on the floor near the shifter can shorten out easy. Is your heater lever in the UP position? (IMG:style_emoticons/default/idea.gif) |
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| rhodyguy |
May 4 2015, 11:21 AM
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#10
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Chimp Sanctuary NW. Check it out. Group: Members Posts: 22,079 Joined: 2-March 03 From: Orion's Bell. The BELL! Member No.: 378 Region Association: Galt's Gulch |
Are the plate wires taped back all the way THRU the hole? If they are chaffing on the hole with no grommet, that might be the problem.
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| Mueller |
May 4 2015, 11:26 AM
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#11
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914 Freak! Group: Members Posts: 17,146 Joined: 4-January 03 From: Antioch, CA Member No.: 87 Region Association: None
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I had a cigarette lighter outlet on my last 914 that was internally shorted that caused some problems.
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| poorsche914 |
May 4 2015, 03:28 PM
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#12
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T4 Supercharged Group: Members Posts: 3,089 Joined: 28-May 09 From: Smoky Mountains Member No.: 10,419 Region Association: South East States |
Heater lever is in the OFF position. I thought of that, also, when the lever was in the ON position. Especially since it is not hooked to anything and never has worked since I've had the car.
Plate wires are inside the trunk. Haven't been hooked up since I've had the car. Cigarette lighter... will check that along with about a million other possibilities (IMG:style_emoticons/default/blink.gif) (IMG:style_emoticons/default/driving.gif) |
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| jim_hoyland |
May 4 2015, 06:01 PM
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#13
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Get that VIN ? Group: Members Posts: 9,286 Joined: 1-May 03 From: Sunset Beach, CA Member No.: 643 Region Association: Southern California
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My fuse 9 has:
Double red/white stripe wire that goes to Hazard flasher switch, fuel gauge and tach Double black wire that goes to seat belt relay and 15 on the ignition switch I think the coil wire comes off 9 too? |
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| poorsche914 |
May 4 2015, 08:26 PM
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#14
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T4 Supercharged Group: Members Posts: 3,089 Joined: 28-May 09 From: Smoky Mountains Member No.: 10,419 Region Association: South East States |
Unfortutately, I am not going to have much time to troubleshoot this over the next few days. When I do figure this all out, I will post here.
In my research, I did find that Fuse 9 controls: Alt charge indicator lamp Thanks for the suggestions. (IMG:style_emoticons/default/aktion035.gif) (IMG:style_emoticons/default/driving.gif) |
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| poorsche914 |
May 7 2015, 05:58 PM
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#15
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T4 Supercharged Group: Members Posts: 3,089 Joined: 28-May 09 From: Smoky Mountains Member No.: 10,419 Region Association: South East States |
Finally got some time to take a good look at wiring and... found it! (IMG:style_emoticons/default/piratenanner.gif)
The tach wire from the relay board to the interior had bare wire poking through one point (IMG:style_emoticons/default/confused24.gif) While driving, this wire would move around and at some point ground out, thus blowing the fuse and causing the problem at random times. (IMG:style_emoticons/default/mad.gif) This time, since I was not driving the car, the wire remained grounded (IMG:style_emoticons/default/dry.gif) So after chasing wires that lead to no results, the culprit was found, taped up, and my 914 will be driven this weekend (IMG:style_emoticons/default/aktion035.gif) (IMG:style_emoticons/default/driving.gif) |
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| Shadowfax |
May 8 2015, 07:41 AM
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#16
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Show us the meaning of haste Group: Members Posts: 509 Joined: 19-January 15 Member No.: 18,340 Region Association: South East States
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QUOTE(poorsche914 @ May 7 2015, 06:58 PM) Finally got some time to take a good look at wiring and... found it! (IMG:style_emoticons/default/piratenanner.gif) The tach wire from the relay board to the interior had bare wire poking through one point (IMG:style_emoticons/default/confused24.gif) While driving, this wire would move around and at some point ground out, thus blowing the fuse and causing the problem at random times. (IMG:style_emoticons/default/mad.gif) This time, since I was not driving the car, the wire remained grounded (IMG:style_emoticons/default/dry.gif) So after chasing wires that lead to no results, the culprit was found, taped up, and my 914 will be driven this weekend (IMG:style_emoticons/default/aktion035.gif) (IMG:style_emoticons/default/driving.gif) Cool! Thanks for posting the fix. |
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| Tbrown4x4 |
May 8 2015, 05:08 PM
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#17
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Senior Member Group: Members Posts: 703 Joined: 13-May 14 From: Port Orchard, WA Member No.: 17,338 Region Association: None
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YES! Thanks for the closure!
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| stugray |
May 8 2015, 05:22 PM
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#18
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Advanced Member Group: Members Posts: 3,824 Joined: 17-September 09 From: Longmont, CO Member No.: 10,819 Region Association: None |
QUOTE(poorsche914 @ May 7 2015, 05:58 PM) Finally got some time to take a good look at wiring and... found it! (IMG:style_emoticons/default/piratenanner.gif) The tach wire from the relay board to the interior had bare wire poking through one point (IMG:style_emoticons/default/confused24.gif) While driving, this wire would move around and at some point ground out, thus blowing the fuse and causing the problem at random times. (IMG:style_emoticons/default/mad.gif) This time, since I was not driving the car, the wire remained grounded (IMG:style_emoticons/default/dry.gif) So after chasing wires that lead to no results, the culprit was found, taped up, and my 914 will be driven this weekend (IMG:style_emoticons/default/aktion035.gif) (IMG:style_emoticons/default/driving.gif) Sorry but I dont believe that a shorted tach wire should blow a fuse. The points ground that wire for every spark so it shouldnt pull any more current than the points being closed. It could cause the engine to lose spark & run like crap or stop entirely though. You are talking about the purple Black wire (pin 7 from front of the relay board, pin 5 on the engine harness side)? |
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| poorsche914 |
May 8 2015, 07:05 PM
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#19
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T4 Supercharged Group: Members Posts: 3,089 Joined: 28-May 09 From: Smoky Mountains Member No.: 10,419 Region Association: South East States |
QUOTE(stugray @ May 8 2015, 07:22 PM) Sorry but I dont believe that a shorted tach wire should blow a fuse. The points ground that wire for every spark so it shouldnt pull any more current than the points being closed. It could cause the engine to lose spark & run like crap or stop entirely though. You are talking about the purple Black wire (pin 7 from front of the relay board, pin 5 on the engine harness side)? Yep, that's the one. Maybe it wasn't that (IMG:style_emoticons/default/confused24.gif) All I know is the car is running fine and no fuses are being blown. (IMG:style_emoticons/default/driving.gif) |
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