Pelican Parts
Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help



Go Back   Pelican Parts Forums > Porsche Forums > Porsche 914 & 914-6 Technical Forum


Reply
 
LinkBack Thread Tools Rate Thread
Author
Thread Post New Thread    Reply
Registered User
 
jsteele22's Avatar
 
Join Date: Aug 2005
Location: Colorado Springs
Posts: 78
instant, total death - electrical system

I spent the day replacing all my vacuum hoses and testing fuel injectors. Had things all put back together, and decided to go for a ride. Pulled out the drive, made a (spirited) U-turn on the boulevard, and suddenly engine died. Now there is absolutely nothing working in the electrical system. No lights, no voltage to coil, no starter or solenoid sounds, nuthin.

Battery is fine, battery terminals and connections fine. Engine ground to chassis ground is fine.

I was frustrated enough that i took my other (working) car and went hunting at the junkyard. Picked up a pair of 320i front calipers for $6, and a pair of horns for another $6. Went to Borders and read Wayne's 911 rebuiild book. (I'll buy a copy if i ever get anywhere close to owning a porsche motor...) Anyway, now it's time to head home and start debugging.

Are there any "classic" causes for sudden electrical system death ? I'm guessing the ignition switch (the key) might be one. Any others ?

TIA,
Jeff
Old 09-03-2005, 04:59 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #1 (permalink)
Registered User
 
M. Hendrix's Avatar
 
Join Date: Jan 2003
Location: Savannah, Ga.
Posts: 2,006
Connections at relay box. Maybe you dropped a harness.


M
__________________
I wish I had a dime for every penny I ever had.

http://www.914club.com/bbs2/uploads/blog-1136350347.jpg
Old 09-03-2005, 11:05 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #2 (permalink)
Administrator
 
Dave at Pelican Parts's Avatar
 
Join Date: Dec 1969
Location: Silly-Con Valley
Posts: 14,061
Garage
Send a message via AIM to Dave at Pelican Parts Send a message via Yahoo to Dave at Pelican Parts
"Something" is unplugged. Dig out your voltmeter and start checking for voltage. Start at the battery posts--you should see +12V. Then check the + post to the chassis. Then check the + clamp to the chassis. Then check "hot" parts of the relay board (e.g., the fuses) to the chassis. Ditto the fuse box. And so on.

At some point, you will find no voltage at all. There will be a disconnect between the last thing you checked and the current thing. Check the wiring diagrams for what is connected to which.

--DD
__________________
Pelican Parts 914 Tech Support

A few pics of my car: http://www.pelicanparts.com/gallery/Dave_Darling
Old 09-04-2005, 07:50 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #3 (permalink)
Registered User
 
jsteele22's Avatar
 
Join Date: Aug 2005
Location: Colorado Springs
Posts: 78
A little bit of progress. I pulled apart the steering column to check the ignition switch (I have to replace steering bearings anyway). I did find +12V on the #30 terminal of the key connctor block. I used an ohmeter and as far as I can tell, the key switch is working. So the problem seems to be further downstream.

But there's something very strange. During the course of dismantling the steering column, I disconnected and re-connected the battery. Once I verified that the ignition switch looked correct, I tried turning things on. Suprise ! Parking lights work, instruments lights. I turn the switch to halfway (accessory), and the headlights work. So I decide to go all the way and crank the starter. Bzzt. Now nothing works. Everything electrical is completely dead as before. So I have an idea. I disconnect the battery, wait a second, then reconnect. Once again, I have dash lights, headlights, everything working. This makes no sense at all. It's as if there were a latching circuit breaker in there, only there's not. Hmmm.

Anyway, apart from the impossibility of wat I saw, I did figure some stuff out. After the first failed attempt to start the motor, I of course made a second one. This time, the starter turned and it was like I was home free, only the engine wouldn't start. Usually it fires right up and has never hesitated. So I look around, and see that the blue (25 A) fuse on the relay board is blown. Finally some kind of evidence. I'm 95% sure that this fuse was NOT blown originally, when my problems started. So I look around for any obvious shorts in the engine bay, replace the fuse, and give it a try. The events repeat exactly as before :

* Reconnect battery.
* Lights work.
* Hit the starter. All the lights go out, starter does not crank.
* Disconnect battery, reconnect battery.
* Lights work again. (Fuse is still good.)
* Hit starter. This time, starter turns but engine does not start.
* Check fuse. Now it is blown again.

So the "short" story is that something in the engine bay draws excessive current when I try to start the engine. This blows the blue (25 A) fuse on relay board. I would suspect part of the engine wiring harness has been scraped bare, or a connector which isn't in plain sight has pulled loose and touched chassis or engine ground. I really don't understand the weirdness about having to disconnect and reconnect the battery, but I can live with it. I'm out of 25A fuses, and won't have time to work on this for several days, but if anyone has any BTDT stories about shorts in the engine wiring harness or even just a wild-ass hunch, let me know. I *was* mucking around in the engine bay (replacing vacuum lines, checking injectors) shortly before this whole mess started.

Thx,
Jeff
Old 09-04-2005, 11:38 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #4 (permalink)
Registered User
 
M. Hendrix's Avatar
 
Join Date: Jan 2003
Location: Savannah, Ga.
Posts: 2,006
misplaced + on a -... maybe at the coil?

Starter wire? Look at the starter harness?


M
__________________
I wish I had a dime for every penny I ever had.

http://www.914club.com/bbs2/uploads/blog-1136350347.jpg
Old 09-05-2005, 05:36 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #5 (permalink)
Registered User
 
jsteele22's Avatar
 
Join Date: Aug 2005
Location: Colorado Springs
Posts: 78
Quote:
Originally posted by M. Hendrix
misplaced + on a -... maybe at the coil?

M
Well, I did disconnect the coil when I was doing the Dixie Cup test on my fuel injectors. Of course, I would never, ever, re-connect it incorrectly , but just to humor you I'll give that one a look-see tonight.


Thx,

Jeff
Old 09-05-2005, 08:12 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #6 (permalink)
Registered User
 
jsteele22's Avatar
 
Join Date: Aug 2005
Location: Colorado Springs
Posts: 78
Just a quick afterthought. If the wire to the coil was re-connected improperly, the engine wouldn't run at all. I did do a fair amount of testing w/ the engine on, and managed to drive for maybe 1/2 block before all this hit the fan...
Old 09-05-2005, 08:15 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #7 (permalink)
Registered User
 
jsteele22's Avatar
 
Join Date: Aug 2005
Location: Colorado Springs
Posts: 78
electrical problem SOLVED

I bought a bunch of 25 A fuses and tried tracking down the problem by disconnecting relays, wiring sub-harnesses, etc. In itself, that didn't lead to the problem, but strangely enough one time when I tried cranking the engine actually started ! Cool ! Oh, but no way of knowing what the problem was. Damn ! So I go around to the engine bay and start reving the motor and I notice a bunch of sparks come from deep down under a mess of hoses and wires. Cool! Turns out the red wire that comes from the underside of the Auxiliary Air valve was cracked and shorting to the engine. I pulled the AAR and it turns out the wire is sort of "built in"; I learned this by yanking on it w/ pliers until it ripped out. It sure would have been a nicer design if it came w/ a connector. Anyway, since my car doesn't have heat I won't be starting it up in cold weather; so I just plumbed out the AAR. While I was at it, I yanked the (not working) decel valve as well. (My box of leftovers is getting pretty full...) When I pulled the decel valve, I found a vacuum leak : the little elbow that couples the tiny control hose to the air box had a tiny hole in it; I hadn't noticed it before, but when I held it up I could see a tiny spot of light. So my idle problem is fixed as well.

Took her out for a spin (after re-connecting the steering column), and she ran great. One of these days I wanna get underneath that air box and clean up the top of the engine, replace wires, etc. But for now, I think I'll do a little more driving

Thanks to all who offered help.
Old 09-06-2005, 09:58 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #8 (permalink)
Reply

Thread Tools
Rate This Thread
Rate This Thread:

 


All times are GMT -8. The time now is 02:58 AM.


 
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2018 Pelican Parts, LLC - Posts may be archived for display on the Pelican Parts Website -    DMCA Registered Agent Contact Page
 

DTO Garage Plus vBulletin Plugins by Drive Thru Online, Inc.