Need help: no power after ammeter bypass

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blackhand

blackhand

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After installing an 18" electric fan, new stereo and speakers, and MSD ignition, my alternator was in need of an upgrade. I went with a 75 amp model and decided to bypass the ammeter for safety. I'm 99.9% certain that I followed the diagram provided by madelectric to a "T"(attached).

I ran a 10 gauge wire from the alternator to the starter relay with 14 gauge fusible link. I ran 2, 12 gauge wires with a single 16 gauge fusible link from the starter relay through a grommet in the firewall. One wire went to the black wire near the bulkhead that used to receive power from the alternator. I connected the other new wire to the black wire where it used to attach to the ammeter.

I've triple checked the wiring diagram and this SHOULD work. The problem is that I now have no power inside of the passenger compartment, no ignition, no lights, not even the dome light. The one thing that does have power is the stereo, which is connected directly to the starter relay positive post (I know this because it has a light that flashes when the faceplate is removed).

I'm all out of ideas at this point. Everything worked just fine before I began, except for the lack of amperage. I'm sure that I'm overlooking something simple... Does anyone have any ideas what could be causing this?
 

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I ran my wire directly from the alternator post to the positive battery post.Did not need to disconnect any existing wiring on the ammeter gauge, and I have had no issues with power or charging.
 
Difficult to troubleshoot "by remote" but the fact that you have no power should be easy to find--get the test lamp

Don't discount the fact that sometimes in-harness splices fail, the crimped eyes on the ammeter original wires can fail inside the rubber molded ends, or your own stuff might be flakey.
 
Something missed. I soldered amp wires together, ran wire from alt to relay, bypassing firewall,ran bigger wires to batt in trunk, and cut-off switch. Re-check with ohm meter.
 
blackhand said:
I ran 2, 12 gauge wires with a single 16 gauge fusible link from the starter relay through a grommet in the firewall. One wire went to the black wire near the bulkhead that used to receive power from the alternator. I connected the other new wire to the black wire where it used to attach to the ammeter.
Click to expand...

I'm not sure what "the black wire that went near the bulkhead that used to recieve power from the alt.) The big black wire that is IN the bulkhead connector should be the wire that your new 12gauge wire attaches to that is on the INSIDE of the car. However this should be the same wire that was connected to the ammeter that you connected the other 12gauge wire to. Both these "old wires" should have been a 10 or 12 gauge wires inside the car.

I would use a voltmeter insid the car at these points of attachment to make sure you have 12 volts inside.

The only reason the stereo is blinking is because you have it powered on the battery memory side of the radio at the starter relay. It won't actually work till you get the ignition keyed side of the radio powered.

On a side note, where are you getting power for the electric fan??? It should be on a relay that gets it's power feed from the battery or the starter solenoid stud.
 
nothingbutdarts said:
On a side note, where are you getting power for the electric fan??? It should be on a relay that gets it's power feed from the battery or the starter solenoid stud.
Click to expand...

Roger that, it's hooked up to a thermostatically controlled relay and powered straight from the solenoid stud. Works great 8)

All the connections should be good, I used crimped, soldered, and insulated butt connectors. I'm beginning to wonder if I somehow disconnected on of the wires from the back of the ignition switch. I'll have to go back down and take a look tomorrow.

Thanks all for the help

Daren
 
If the headlights dont work the ignition switch is not the problem.
There was a safety disconnect and fusible link at the bulkhead connector.
If that is still there the fusible link may be blown.
 
RedFish said:
If the headlights dont work the ignition switch is not the problem.
There was a safety disconnect and fusible link at the bulkhead connector.
If that is still there the fusible link may be blown.
Click to expand...

X2. You need to go in and check with a voltmeter to see where you lost the power.
 
What about the red wire that was on the other post of the amp meter? It should be one big loop like the diagram you posted. Also yes check the wires on the ignition switch. I had one come disconnected and the car wouldn't start. I did use the same diagram that you did from madelectric and I have had no problems.
 
Found my gremlin! For some reason one of my high speed, low drag crimp/solder/shrink butt connectors had 12.3v input and 0v output. I guess I took it for granted that these fancy butt connectors would work perfectly.

The cuda's running great and I'm back on the road:burnout: BTW, this fairly simple rewiring works great; I can really tell the difference in the brightness of my instrument lights.
 
Very good. I'll bet you could've yanked the wire out of one end of that connector
 
I learned years ago never to use butt connectors. All I do is strip about 1/2" off the wire ends slide on some shrink sleeve, lay the bare ends over each other. Then heat them up, solder them together then slide the sleeve over them and heat it up and shrink it. It's the most permanent way and seals it completely. That's actually the same way the factory did it.
 
StrokerScamp said:
solder them ............. That's actually the same way the factory did it.
Click to expand...


I don't know what years you speak of, but the ones I've seen--about 64 through about 73---were welded, and they have failed.
 
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