Any advice in this matter would help greatly. I have put an 89 2.8 L engine from a firebird into an 86 firebird. The main reason for doing this was to replace the worn down engine that was already in there. Even though there are a lot of similarities in the two engines, I have encountered a few differneces in the wiring hookup positions and colors. The biggest problem I have right now, is that the alternator is not charging the battery. I have already checked the grounds, the junction box, fusible links, and I have checked to see if the alternator and battery are working. All are working correctly. I have also been studying both of the wiring diagrams for each car. Also, from what I understand, if a lightbulb in the dashboard is burnt out, it could cause a "no charge" situation.(mine is working unfortunatly) It was from this, that I have been basing all of my experemental and logical wiring hookup changes. Im getting all of my wiring info from the chilton book. I am in over my head with this problem, so if anyone can give me some help on this, it would be appreciated greatly.

 

Was the '86 alternator the old style GM alternator? Is the '89 alternator the new style GM alternator? They are wired a little differently. The old style used a square plug with two wires (typically red and brown) and a single post with a big red wire. The new style uses a different style plug (usually with 3 or 4 wires, or at least 3 or 4 terminals inside the alternator, even if only 1 or 2 wires are run to the alternator) and still uses the post.

Cross reference the manner in which the two alternators are connected on their respective years. Look at the terminal letters (BATT, S, V, ect.) on the alternators and make sure that the wires go to the right terminals (match letter for letter). You should have a big red wire running from the post to the battery. Then there is a feedback wire coming from the cars electrical system that runs to the regulator/rectifier, this ensures that the alternator is putting out the correct amount of power to keep the battery at the proper level of charge. A lot of people omit this wire or connect a short piece from the battery post to the reg/rect terminal. They think that these alternators are all set up as "one wire alternators". This isn't true, and can cause low speed and/or high load charging problems, as well as overcharging at high speed. Ideally your alternator should put out 14 volts at all times. If it isn't then something is wrong.

There will be a wire for the stator as well, which is typically brown, tan, or dark green (at least on V8 cars, I can't say for sure on a V6). This needs to be hooked up too.

There is also a terminal for the voltage readout gauge in the car. This can be omitted, and you can wire the gauge directly into the car's power circuit, especially if you run an aftermarket gauge like I do.

 

To answer your question about the alternator, I actually bought a new gm and it is the new style. The thing about the feedback wire that you were also talking about, is that there isnt any power comming from that wire, even if the car is on. Do you have any idea what I could connect that wire to? I heard that maybe I could connect it to a hot wire, but there are some problems that could go wrong. For example, the alternator could overcharge the battery.What do you think.

 

You will need to connect the feedback wire to the cars electrical system, but where you connect it is important. It needs to go to a source that has 12volts keyed power (connecting it to a constant hot will damage the regulator/rectifier). Ideally you need to connect this wire into the system at a point after the system has been loaded.

What you are trying to do is give the alternator a clear and accurate message about how much draw the system is creating. That will allow it to adjust its output to compensate. You might try running this wire to the 12 volt keyed port in the fuse panel. Monitor your voltage output and see if any problems exist like voltage spikes or low charging. If these problems occur then you need to try another location. It's tough to say exactly where without seeing a wiring diagram of the car. In the old days the bus bar on the horn relay was a good location, because that's where nearly everything on the car drew its power.

 

I finally found the problem. It was that the wrong wires were hooked up at the ecm. Now the alternator runs around 14.8 v. Im not completely sure that is a good charge, but I dont think I shuould wory about it. Thanks a lot for helping out.

 

14.8 seems a bit high, but if you aren't experiencing any voltage spikes, and the charge is constant regardless of RPM and load then I wouldn't worry about it.

Glad to hear you got it figured out.

 

Thanx a lot for your help.

 

No problem, let me know if you need any more.