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rjsmith530's Avatar
 
Join Date: Jan 2002
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Angry Interesting Electrical Problem - Help!

I finally got some time to continue working on my big-4 with Webers and I have run into an interesting electrical problem. I got the car running and drove it around the block when it suddenly died (electrically). I discovered that I had no spark and continued to trace it to no power at the coil. My electric fuel pump would not work either while connected to one of the power points of the 4-connecter part of the relay board. I have power to the 14-pin connecter but no power to the 12-pin connector (on the relay board, with the key "on") . There is power at every #30 pin for the relays. All fuses on the relay and underneath the dash are new (and not blown). I got on the phone with Pelican and decided that it was a bad relay board. I installed a new relay board today with new relays and the same conditions exist. Somewhere between the 14-pin connector coming from the battery and the 12-pin going to the coil among other places I have lost 12-volt power. What am I missing here?

Any ideas?

RJS
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Old 11-23-2002, 09:11 PM
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Check out this post in the search forum... my spark is gone
It may just be your condenser or points.
bruce
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Old 11-23-2002, 10:45 PM
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Check that you get +12V on the black wire to the 14-pin connector when the key is on. Check that you have a good ground on the brown wire. Make sure that both red wires going to that connector have +12V as well. (I think that's full-time.)

--DD
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Old 11-23-2002, 10:58 PM
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Unless you have two relay boards, both with failures in continuity between the 14 pin connector (pin9) and the 12 pin connector (pin 7), then at least one of your conditions is false. Disconnect both connectors and put a continuity tester (or ohmmeter) between pins 9 and 7 of the respective recepticles on the relay board and if you find continuity, then you will know that one of your conditions is false.
Good luck.
Phil
Old 11-24-2002, 05:19 AM
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OK guys,

I have done a little more work on it and I am even more confused.

Philiinjax, I test continuity between pin9 on the 14 pin connector and pin7 on the 12 pin connector. I have continuity on the new relay board but not the old. Old relay board is probably bad.

DD, I do have power on pins 12 and 14 of the 14 pin connector BUT the black wire pin8 does not have power when the key is on. I am check voltages by checking ground at the brown wire pin10 and the chassis at the main grounding point near the relay board on the chassis.
The issue is clearly that I do not have power at the black wire (pin8) when the key is switched on. The #9 fuse is GOOD (pin8 connects here) and I do not get power hear at the fuse either. I have continuity from pin8 to fuse #9 .

NO power at fuse#9.

Now what?

If everything is connected the car will turn over (ignition switch works?) but now power at coil and obviously no spark at the plugs.
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Old 11-24-2002, 12:16 PM
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Sometimes the power may be to the conector but not getting thru to the pins. I had a similar problem and after researching the current paths with the electrical schematics on this site. I found the problem was in the connectors. I took a test light pic or a sharp awl and very carefully opened the pins up a little and the contacts were made. Good Luck!
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Old 11-24-2002, 04:27 PM
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Ummm, what year is your car? Now that we're getting into wiring specifics, knowing the year will come in handy...

In the late (74+) cars, at least, fuse #8 does not feed power to the coil. In those cars, the power to the coil comes from the battery, goes through one part of the ignition switch (only when the key is on), and goes to but not through one side of fuse #9, then back to the relay board.

A quick look at the 73 wiring diagram shows the same kind of path for the power to get to the coil.

Dig out the appropriate wiring diagram for your year of car and start tracing! My guess is that you'll either find a bad ignition switch, or a bad wire where a connector crimps onto it.

--DD
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Old 11-24-2002, 04:34 PM
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rjs,

I have made a big mistake. In my previous posting when ever I referred to pin 9 of the connector T14, I really meant pin "8". I guess my old eyes aren't as good as they used to be.

Please go back and reevaluate my previous posting. Thanks,

Phil
Old 11-24-2002, 05:24 PM
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Thanks for all the replies! FYI it is a 73.

Philinjax, pin 9 to pin 7 will have continuity as long as the relay is in because pins 85 and 86 are straight thru on all the relays. Pin7 of the 14 pin connector and pin5 of the 12-pin have continuity too.

I will work on the connector next week and investigate the possibility of a bad ignition switch. When it is switched to on other electrical items work but no power at pin8. The car does turn over so it would have to be a flaky failure at the switch. Will let you know in a few days.

RJS
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Old 11-24-2002, 06:42 PM
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Have you followed all the steps in Brad's article on troubleshooting the fuel pump at:
http://members.rennlist.com/pbanders/FPChecklist_frame.htm, you said it doesn't run and the pump and voltage to the coil can be related. I have used it on our stock 914 and my race car since it still has the relay board and uses the relay for supplying power to the fuel pump. I have a kill switch in the circuit which makes things a little more complicated, but the idea is the same. Good luck.
Old 11-25-2002, 09:39 AM
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The ignition switch is not one simple switch. It has several separate switches in one housing. One of those internal switches could be bad... Or it could be something else.

See if you can locate pin #30 on the switch (or the wire that goes to it) and check for +12V there. It should be present at all times.

--DD
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Old 11-25-2002, 11:11 AM
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DD,

It looks like it was the ignition switch that was the problem on my 73. It was cracked.I bought a new one from PP and installed it. I have switched power now at the coil however I have run into two new problems. Since I installed the switch the "key in lock buzzer" does not work anymore (no power to it) and I still do not get any spark from the coil. I get power on the primary and secondary sides but no spark if I turnover car and hold the coil wire just off a ground point.
I am using a new Bosch "Blue" coil. Coils rarely fail but I also tried my old stock coil
that worked prior to installing the bigger four and webers. FYI-I have kept all the FI parts and have another 2.0L case. Someday, I will revert back to FI - I know you are a big fan.

RJS
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Old 11-29-2002, 10:49 AM
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