|Originally posted by theogre:|
[QUOTE]Originally posted by TXGOOD:
My alternator is putting out right under 16 volts.
I had it tested today and it passed.
I checked the wiring plug and the Red goes to L and the Orange goes to S.
I would assume that the PCM is somehow not telling the alternator how much to charge.
If there was a problem in the Orange wire could that cause the alternator to charge high.
Oh, I`m not relying on the gauge although it`s pretty accurate.
I have measured voltage at the battery and at the alternator output post.
So the "Red goes to L and the Orange goes to S?" Doesn't sound right and likely making the Alt is too high volts. Do Not run the car like that because pushing many E-parts into over volts even at 16v. (Many E-parts have only 16V Capacitors like many Radios connected to "12v" input power. While rated 16v to 20v when new... Decades later the cap ratings can degrade depending on type.)
If Red wire is bigger gauge then Orange then more likely have side plug wires wrong.
Some PCM controls the Alt. Others just monitors and plays "man in the middle" w/ battery light.
PCM controlled Alt can use F and/or P terminals as well. (See my Cave, CS Alternator
I don't have alt wiring for that engine but many PCM controlled are this way if only two wires to side plug...
PCM Should make Alt to Turn On/Off only at best. Like the Battery Lamp did before. Using L or other pins But Not S
Alt Output and S pin should be splice together somewhere nearby in the engine harness as shown is my Cave, Alternator Sense
"Unplug" alt out and side plug. And "unplug" the PCM too. ECM/PCM may be damage/kill for next step.
Should see 0Ω on the wires to output and S terminal if wired as shown there.
If not check Alt Out and Red wire currently going to L for 0Ω.
If neither has 0Ω then need FSM, AlldataDIY, etc for the donor car to find right Alt wiring.
Example: Some PCM use Side plug P pin to see Alt RPM and could "trip a code" for belt slipping etc.
I`m just going by what was said in this post.
The Red and Orange wires I`m referring to are in the plug that goes in the side of the alternator.
The larger Red wire is connected to the bat post on the alternator. https://www.fiero.nl/forum/...160323-2-123056.html
[This message has been edited by TXGOOD (edited 10-13-2021).]