Hi guys. Been a while since I posted here. Cliff notes. I spent 4 years restoring my car and missed a gas line clamp. Ran for 5 minutes and burnt to a crisp..... anyways. I’m back at it. Need a little help with wiring. I have the wiring diagram Few questions. It shows 3 wires going to the alternator. It looks like only 1 plug on the alt? Where’s the other wires go... What’s the little plug near the horn relay?
Last edited by jman01; 04/29/2106:15 PM. Reason: Updated
Hi, sorry to hear about your troubles but I have seen it before. It is the main reason I only use the factory steel line on the pressure side of the pump to carb. and not rubber. Even with a small stream squirting out from a bad connection or cracked hose the engine will still have enough pressure to stay running and keep pumping that stream of gas all over your engine until it finally catches fire. As far as the third wire that is the main + wire from the stud on the back of the alternator that goes to the battery and charges it. from the diagram you have it is hard to tell what that other thing is near the relay unless its just shown separate to show the wiring for the key buzzer that is in the originals. I don't believe the aftermarket relays have it. I did not take the time to go through a whole diagram but here are some from Harold B's site, and a detailed picture of the horn relay wiring with warning buzzer. The only other thing I can think of is mounted on the firewall above the master cyl. and is used if you have a pwr. conv. top and or pwr. windows but the full diagrams on Harold's page will tell the tale. https://www.firebird400ho.com/mdocuments-library/ I just noticed on the bottom of your post it says 67 FB if 67 they did not have the key warning buzzer so make sure the diagram you have is 67 only and not a hybrid.
Just a thought on your alternator plug question. The original externally regulated alternator had the 2 wire plug you described. Many folks changed over to the later internally regulated type that had only the larger single positive post you mentioned on yours. Or do you have the wrong (later, internally regulated) one on your car?
Everything is brand new with the motor and nothing is original. I do have a new alt with just the one post. What happens with the 2 wire plug when you convert?? Just cap it??
This may be a trip to the resto shop. I tried to start the car. It fired up. But it Kept cranking after I turned it off and pulled the key. I had to pull the battery cable. Thoughts?!?!?
How did you connect the alternator? Post a photo. I recall, when connecting an internally regulated alternator, that there was a need to install a diode inline with one of the wires. I posted a lengthy description at that time. I’ll see if I can find it..
I'm a hobbyist. Not a professional. Don't be hatin'!
“I went straight to option 2 above(install 5 pin relay). Followed MSD's Tech advice to the letter. Another beautiful installation I have to say. All splices soldered and heat shrinked. (Dad would've been proud.) Engine STILL wouldn't turn off!!!(Dad would have laughed!) Sun of a BIOTCH!!! So, I studied the wiring diagram in the service manual again(remember, I only have 2 wires connected to my Voltage Regulator...Black w/white stripe and Blue...to No.1 and No.2 terminals). The book says I had 2 more wires and I wanted to find them. I unwrapped the wire "loom" in that front area and wouldn't you know it...there were the missing wires...along with the unattached ends of black w/white stripe and Blue wire from the voltage regulator!!!! What the frig? My poor baby. No wonder she gets crabby sometimes. she's a mutant!
Then I figured a previous abuser had swithched to an internally regulated alternator. I never paid any attention to it since I had that voltage regulator right there on the radiator support and I didn't have any battery/charging issues.( I should win some sort of Dumb A$$ award!)
Here's the good part: I noticed one of the wires coming from the alternator was spliced directly into the BROWN wire from the harness. A BROWN wire was supposed to be connected to the No. 4 terminal on the voltage regulator. Hmmmm...???? I cut that wire and the engine turned off properly at the ignition switch but, the alternator wouldn't charge(according to my gauge in the car). I then installed the diode. Engine turned off properly AND the alternator charges properly. The diode worked!
Tomorrow, we test drive...”
The diode is like a one way “valve”. It only allows electricity to flow in one direction.
Hope this helps.
I'm a hobbyist. Not a professional. Don't be hatin'!
On the alternator there are 2 types of gm internally regulated alternators one has 3 wires like our original externally regulated alternators but uses a flat plastic plug instead of a square one like our originals and the other type which is more modern then the former uses just one charge wire from the back of the alternator to the battery and is self energizing. It sounds like you are using the latter true one wire. The other 2 smaller wires in the plastic plug you are talking about were used in the original setup and in the 3 wire internally regulated alternators. One to the key switch to energize the alternator and one to the charge indicator lamp in the dash. Obviously you don't need the one that is switched by the key to energize the alternator in your one wire self energizing alternator so you can cap that or use it for keyed power for something else if you want. the other wire for the dash light can be capped but you will have no gen/alt. light. If you are using an aftermarket volt gauge then you don't need it anyways. I don't like 1 wires because I like to run original stuff But if changing to an internally regulated alternator I run the 3 wire for compatibility with the factory wiring, you just have to change the one different style plug. As far as the starter not disengaging That sounds different from what Bronzebird is describing in his post about a running engine that can't be switched off. If the starter solenoid is only engaged and engine turning over in the start position and with engine not running but key in the on or run position does not turn over. But after the starter is engaged with the key in the start position and the engine starts but the starter gear wont disengage with the flex plate/flywheel that is a mechanical problem. Only 2 possible problems cause this the first is a starter gear that does not have the proper clearance from the flywheel and needs to be shimmed to the proper spec. I think the spec is one sixteenth of an inch but don't go by my memory. You can use a drill bit between the 2 gears to get your measurement. There must be videos on YouTube describing how to do this just type in how to shim a gm starter It is a very simple procedure and should be done whenever installing a new or different starter in your engine. You could get lucky and it be dead nuts right out of the box but in my experience as a former mechanic most people don't have an experienced enough ear to be ale to tell if the gear depth spec is to big or to little as long as it works and does not sound terrible. The problem is down the road in time when the flex plate/ flywheel teeth corners get all chewed off and by then it's to late. If your gear depth is in spec then the starter has a mechanical solenoid problem which in most cases will show up in a simple bench test.
While typing my former post your pictures popped up. You do not need an external regulator with an internally regulated alternator. I don't want to sound like a jerk but that is really basic stuff and My advice would be to get some help by someone with mechanical experience or don't connect wires until you have double and triple checked and keep the right style fire extinguisher very close by.
The other wider spaced double plug is for the washer pump that is mounted to the front of the wiper motor, yours may be missing if so not a huge deal. On you alternator struggles you could just replace the alternator that came with that engine with the correct externally regulated one and make everything plug and play. could be the easiest and cheapest option for your skill level. Food for thought.
While typing my former post your pictures popped up. You do not need an external regulator with an internally regulated alternator. I don't want to sound like a jerk but that is really basic stuff and My advice would be to get some help by someone with mechanical experience or don't connect wires until you have double and triple checked and keep the right style fire extinguisher very close by.
I’ve been working on cars for 40 years. I’ll be just fine. Coming into a project after someone starts it sucks. I’ll trace everything...
I didn’t realize the alt I have is 3 wire compatible.. I looked and didn’t see a plug. It was capped on the inside. I bought a small wire adapter that should solve the issue. 2 more unidentified wires and I’ll be looking to start it up! Not sure if this is part of the new harness or part of the efi. They are connected together and were attached to the positive side of the coil. Anyone?
Got the car running. Briefly. Lol. Still cannot identify those 2 wires. Looks like they come out of the firewall plug under the master cylinder closest to the distributor...yellow and white with red or pink stripe they are connected together. The white wire isn’t a standard coated wire. It’s more like shielded. Anyone? I’m so close..
