Help! '73 electrical problems

JMatta · 09-08-2004, 01:33 PM

My '73 has developed an electrical failure. The car was converted to Webers, from injection, by PMO in 1977. I recently had the fuel pump go out, which I replaced. The pump has gone out again, but also the wipers and the parking brake warning light (my guess is the original pump was fine). After jiggling the turn signal stalk and accidently honking the horn, the pump and wipers came back. I was driving the car around the block when everything went dead. I now have no fuel pump, signals, starter and parking brake indicator. When the ignition is turned on, the oil pressure light indicates, headlights work and wipers, nothing else. This car is primarily track, but is streetable. A cursory check of main grounds did not turn up anything. Any experts out there have a clue where I should go from here?

Kurt B · 09-08-2004, 07:29 PM

it's gotta be the ignition wiring. Once you turn on the accessories or higher, you power the entire electrical system, so I'd start there. It's pretty easy to take the steering column plastic off and get at the wiring in there as well. Probably just a simple short somewhere in there.

RoninLB · 09-08-2004, 07:40 PM

what happens when you jump battery volts into the ignition sw "on" connector ?

JMatta · 09-09-2004, 02:13 PM

Update: Took steering column apart, checked all wiring and grounds. Pulled all pin plugs under dash, cleaned, re-installed. Checked all major grounds, took apart, cleaned. Still no power to turn signal switch, tach, parking brake indicator and fuel pump. Starter came back! Car has emergency battery cutoff, checked all leads and grounds; pulled all relays, cleaned, re-installed. Could a bad relay cause this problem?

RoninLB · 09-09-2004, 08:18 PM

Quote:

Originally posted by RoninLB

what happens when you jump battery volts into the ignition sw "on" connector ?

JMatta · 09-10-2004, 04:28 AM

Not sure what you mean by "jumping battery volts into switch on connector". Care to elaborate?

RoninLB · 09-10-2004, 05:13 AM

Quote:

Originally posted by JMatta
Not sure what you mean by "jumping battery volts into switch on connector". Care to elaborate?

Connect 10ga wire from battery positive to ignition sw "on" terminal while maintaining all stock wires. You can buy those Y wire connectors if it makes the job easier. Start car in routine manner. If problems are eliminated then you have a prob at the sw. It could be a bad connection at the sw feed connector or "on" output. It could be a bad connection at the bulkhead plug in the cabin, etc. Or the sw may be kaput. If your testing for voltage use a test lit with at least a 12 watt bulb, not a meter.

the point is that you'll have a specific area to repair if the new jump corrects your prob.

JMatta · 09-10-2004, 02:40 PM

Thanks for the explanation. I'll definately try this next, as time permits. I've pretty much exhausted other avenues. Do you have to be a magician to get the ignition switch out? There is absolutely no room up in there. I see Pelican sells the ignition core in the electrical parts area.

RoninLB · 09-11-2004, 05:12 AM

Quote:

Originally posted by JMatta

Do you have to be a magician to get the ignition switch out? There is absolutely no room up in there.

I see Pelican sells the ignition core in the electrical parts area.

not a magician, but being a double jointed midget helps..

This is what I did and suggest+.
Remove steering wheel after marking position of spline.
Remove ign sw face plate.
Drill or Dremel for a screwdriver or easy out the non-theft/break-off bolt/ ign sw fastening screws.
MAYBE, look on foreward bulkhead plugged hole to insert from trunk a very long screwdriver to reach top small screw of switch. The screw May be for the ign sw not the headlight sw. Or use patience removing top screw. But Wayne doesn't mention the top holding screw in his book so maybe it's for the headlight sw.
If necessary remove headligt sw for more room.. it may make it easier. Headlight sw is easy unless it has the top pia fastner screw.
Not sure if you have a steering wheel lock? If so loosen fastener ONLY what's necessary. Wayne mentions in his book that it may already be loose.

New switch.. Yep, get it from Pelican Parts . IMO if the ign sw has over 100k miles replace the sucker. An old sw is a prob waiting to happen imo. Then you can try the functioning of the new sw as per your elec prob.

The project is on p212 of 101 Projects for Your 911.

enjoy

JMatta · 09-11-2004, 07:42 AM

Thanks for the insight RoninLB...I was able to access the small screw on top with a cut off screwdriver; the screws were both loose top and bottom. I may be able to get the screw out, but replacing could be quite difficult. My car has >100k and a steering lock. Hope to run the test today and that will tell me the next step. Maybe I need to order Wayne's book while I'm at it. Jerry

RoninLB · 09-11-2004, 08:54 AM

Quote:

Originally posted by JMatta
but replacing could be quite difficult.

I might use masking tape in such a situation.. or allow a small magnet to lay on the screwdriver shaft.

fwiw, Waynes book is like no other. A pro might pass it by 'cause he'll see 10-20 911s a week. A weekend wrench will find it orgasmic.. no kidding

pwd72s · 09-11-2004, 09:46 AM

Quote:

Originally posted by RoninLB
not a magician, but being a double jointed midget helps..

Now we all know Ron's secret.

JMatta · 09-11-2004, 09:48 AM

Sat noon update: All terminals on ignition switch test positive. Two red power in, three power out (Red/Ylw, Red/Blk, Ylw). However, have determined the 4th terminal (red/Blk counter-clockwise) is where the fault lies. This feed should power the accesories which I am missing, i.e. turn signals, fuel pump, prk brake indicator. I guess at this point, my only option is to trace wherever this feed goes. Any suggestions would be helpful.

Early_S_Man · 09-11-2004, 10:38 AM

Sounds like you need to change the electrical portion of the switch ... the key and mechanical part stays in place for an easy repair!

RoninLB · 09-11-2004, 10:45 AM

Quote:

Originally posted by Early_S_Man
Sounds like you need to change the electrical portion of the switch ... the key and mechanical part stays in place for an easy repair!

end of story... thanks

JMatta · 09-11-2004, 12:54 PM

When I apply power to the out terminal, just as the key does, (as RoninLB suggested) I have the same electrical fault. Therefore, I have ruled out mechanical failure. Today I measured the voltage at the fuel pump; it only measured .49 volts? The wiring diagram to the pump looks quite simple, however, I haven't been able to figure this one out as of yet. I certainly hope I don't have a bad wire in the harness through the tunnel to the rear of the car! That wouldn't explain why the wipers don't work however.

RoninLB · 09-11-2004, 01:21 PM

Quote:

Originally posted by JMatta

When I apply power to the out terminal, just as the key does, (as RoninLB suggested) I have the same electrical fault. Therefore, I have ruled out mechanical failure.

cool.. a new chapter.

I followed Kurt's lead on this one with a single sentence post..
----- "what happens when you jump battery volts into the ignition sw "on" connector ?"

For entertainment you could at least install a 3-4amp in-line fuse for the un-fused dash lights. I forget what the amp spec is! What I did was use a 4amp re-setable marine circuit breaker.
It's not vapor proof but it's very doable. It's about
5/4x3/4x3/8 and cost $10

RoninLB · 09-11-2004, 01:44 PM

Quote:

Originally posted by pwd72s

Now we all know Ron's secret.

after another reading it is pretty funny..
another reality check. thanks

I've up since 6:30am yesterday. Yesterday was a beautiful day after days of hurricane fading outer storm on/off rain and was waiting for a friend to finish erand and we planned a ride. I love carbs. He never notified me of his change in plains, again. Wasted all day/no ride waiting and multi-tasking with him 1/2.. like WTF.
At 8pm I hit garage for mindless tension release and adjusted door glass and installed Rod Birch's high end Focal tweeters. Finished car at 6am. While waiting for a 9-11am appointment I did clean clothes engine tweaking.

oh yeah Only the Focal tweeters were up-graded and cost $250.
I think your gonna like them.

JMatta · 09-13-2004, 12:59 PM

UPDATE: Thanks to all whom gave input regarding the failure on my car. Turns out the CD (capacitive discharge) box was bad. Interesting the way the car is wired that unrelated circuits would also go dead. The CD box feeds into fuse block 8 in the luggage compartment, where it then branches off to the fuel pump, etc. Hot wiring the system by-passing the box solves the problem.