My question, or possible problem, involves the charging system of my ’87 Camaro RS 2.8L. Please excuse the possible ignorance as I am new to electrical systems and the long post, I wanted to give as much info as possible. The following components are installed:

ACDelco Alternator
10463014 (P/N)321-312 17J1 100 A – as read from the alternator, the P/N I added
Purchased about 1 month ago
3 wire connector (RED, TAN/WHT, BRN) + BATT

Exide Battery
NASCAR Select 800
P/N: 75-84N
800CCA load test amps 310
Purchased yesterday – manufactured Mar ‘02

My questions are basically what readings does the alternator take to determine whether to apply charge to the battery or not and how does the voltmeter gauge in the dash receive it’s readings?

My questions stem from the overall feeling I receive from my car and some physical signs. Whenever the voltmeter gauge needle sits at the bottom of the 13 line, which is usually first start in the morning, or a new alternator, or having the battery disconnected for a day, the car runs very well – plenty of power and smooth acceleration through the RPM, the coolant fan comes on at ~225-230 degrees, etc. – and the voltage reading will not change with the added load (ie. Radio on, A/C with fan on HI with accompanying coolant fan, Hi beams on – the reading will drop with the initial addition but instantly recover to just under 13).

However, which is my concern, when the voltmeter gauge indicates ~9-10, it doesn’t run as well. The coolant fan comes on at ~240 degrees and sometimes not until just before the red, there is a noticeable power decrease where accelerating in first gear feels sluggish until ~3900 and then a sudden burst, randomly encounter Code 34 (MAF), the increase in load will drop the indicated voltage to 8 and then will recover to ~9-10. Basically it just feels like something is wrong.

Some readings I took based on other postings:

Engine running:
- Voltage between battery terminals: ~13.7 v
- regardless of the load or voltmeter gauge indication
- Voltage between BATT on alternator and neg terminal: ~13.7 v
- always same as battery

Ignition in run position, engine stopped
- alt. and RED wire: ~11.2 v
- alt. and TAN/WHT wire: ~11.5 v
- alt. and BRN wire: 0.00 v
- Voltage between battery terminals: ~12.6 v
- Voltage between BATT on alternator and neg terminal: ~12.6 v

Ignition off
- alt. BATT and wire: 12.0 v

- Jacob

 

Good and complete information. Your problem is the brown sense wire. It should have battery voltage with key on in either run or start. The sense wire is what tells the regulator in the alt. when to apply charge. It's source voltage comes from the fuse panel 20A fuse marked C/H-Fan. It then loops around through a diode to the alternator. You are basically running off the battery at this point. Find where you are losing the voltage and your problem is solved.

 

Thanks for the help – were you referring to the BRN wire with the 0.0v reading? I traced that back and it ends at the instrument cluster connector C1 slot 14, and doesn’t go through a fuse. In addition, there is not an accompanying lead on the printed circuit to supply voltage to that wire, guess it wasn’t meant to be used. This connection ends at connector L on the alternator.

The TAN/WHT wire, which does have the voltage and is at connector I on the alternator does go through the 20A fuse (C/H-Fan). This wire shares the circuit with the coolant fan relay, which is new, and eventually changes to the BRN wire at C221 (by the ECM) that continues to the 20A fuse.

The voltmeter gauge receives its power from a PNK/BLK wire from the 10A Gauges fuse at connector C1 slot 2 on the instrument cluster. The PNK/BLK wire continues from the 10A and connects to the ECM. The voltmeter ends in a ground on connector C2 on the instrument cluster slot 9 which is ground G200.

Not sure where the 20A fuse receives its power, it is an orange wire. I have a shop manual for my car which has detailed circuit diagrams which has helped alot, however, it does have a contradiction about the alternator connector L circuit. The diagram for the charging system indicates the BRN wire ends at connector C1 slot 14 and connects to the voltmeter gauge while the printed circuit does not have a connection at slot 14, go figure.

I do have a question about the ECM. I understand that it does have a voltage regulator which seems to be supplying power to the PNK/BLK wire and the 10A fuse, continuing to the voltmeter gauge. What it the voltage regulator in the ECM used for? Could that be the problem? Maybe the ECM is starting to have problems?

Part of my testing I pulled the 20A fuse while the engine was running and the vehicle ran consistently poor – sluggish and rough. The issues I’m having aren’t consistent. They happen mainly at initial acceleration, 1st gear, and I have to apply excess fuel or the car will stall.

Any ideas? The printed circuit looks fine.

 

Your work was not in vain. You may have stumbled across something that has caused questions here more than once. Please go to www.alternatorparts.com and scroll down to the free online service manual for the AC Delco CS alternator. They have a variation that only uses two wires. The red batt line on the rear, and the I wire. Sounds like what you have. They state that there two different regulators used. They are stamped accordingly on the regulator module which you may not be able to see. What you have wiring wise disagrees with both my manuals and they are actual reprints of GM service data. I checked my 89 and all three wires have battery voltage on them. You may very well have the wrong alternator for your application. There is a simple fix however. Disconnect the battery and splice into the brown wire from the tan/wht. This should start the alternator charging if it wants a three wire hookup. Please let me know if this solves the low volt problem as it is something I will make a note of. If it DOES fix your problem, I would go back to the supplier and have him double check part #'s. Keep me posted. As far as the ECM is concerned it is not related to charging. The ECM has internal regulators for it's various circuits but has nothing to do with alt. operation. LOL, Dan

 

Dan...thanks for the info.

I found the problem, however, it didn’t have anything to do with the alternator. The braided ground strap connecting the engine to the frame was loose and dirty. After cleaning all of the parts in the connection my car is running beautifully. Even the coolant fan comes on at 223 degrees, right where the manual says it should. I cleaned the negative battery connection to the engine as well.

I looked at the online manual for the CS-130 and it indicated that the sense wire “may connect to either "L" or "I" or both.” Suppose in other GM vehicles the L terminal is used, or maybe in other versions of ’87 Camaros? I too have the reproduction shop manuals for the ’87 year Camaro, mine are a beautiful 80’s ugly brown, which I purchased from Helm Inc., and when the schematics reflect the actual wiring it’s been a great time saver. This has been the only time I’ve found a contradiction in the manual. This is fine, ‘cause I’m having fun learning about electrical systems and the other systems of my car.

Again, thanks for all of your help. I have another question about engine RPM’s at ignition (RPM’s climb to 2300 for about 1 sec then drop to normal idle at ignition/first start), but I’ll create another post for that.

Jacob

 

Glad to see you found it. I have worked on quite a few of these TG's. Have never come across one wired for 2 wire operation. It is logged in to my notes. Dan