I just looked at the wire diagram for your alternator and it doesn't show the pcm in the diagram having anything to do with the alternator.Key on engine off test the white with a green tracer wire it should have battery voltage to it.Also key on engine off check the black wire with a white tracer it should have battery voltage too.

Answered by saturntech9 (expert)
23,190 answers provided

Why would you think the PCM is bad? I read that the voltage is regulated by a voltage regulator, not the PCM. Check wiring harness and voltage regulator. Test this way.
ON-VEHICLE TESTING

ALTERNATOR PERFORMANCE TESTING

1. If battery is overcharged go to BENCH TESTING . If battery is undercharged, check
alternator wiring harness connections and drive belt tension. Ensure battery is fully charged.
Connect a voltmeter to alternator "B" terminal and ground. Connect ammeter positive lead to
alternator "B" terminal. Connect ammeter negative lead to positive side of battery and start
engine.
2. With all accessories off, increase engine speed from idle to 2000 RPM and read meters.
Voltmeter reading should be 14.4-15.0 volts at 68°F (20°C). Voltage reading will vary
depending on regulator case temperature. Ammeter should read about 10 amps. Turn engine
off.
3. If voltage is higher than standard value, check brush ground. See BENCH TESTING . If
brush ground is okay, replace IC regulator.
4. Load test with engine running at 2000 RPM and headlights and heater blower motor on. If
current is less than 20 amps, go to BENCH TESTING .
CAUTION: DO NOT confuse polarities of IG terminal and "L" terminal. DO
NOT create a short circuit between IG terminal and "L" terminal.
Always connect these terminals through a test light. DO NOT
connect a load between "L" and "E" terminals.

Answered by merlin2021 (expert)
18,145 answers provided

As you can see the regulator is built into the alternator, inspect wires and replace alt if OK.

Answered by merlin2021 (expert)
18,145 answers provided

Please read question and all answers....I checked the wires on the plug to the alternator and I get battery voltage to both. All wires are good and alternator is good. Could it be that the starter is draining the system, since the PCM isn't in question?

Response from shvlhead68
4 questions asked

So the MIL does not come on with key on engine off? If you post your email, I will send the info you need to repiar the circuits, it's 36 pages with diagrams, so too much to post here.
Drop an email to
merlin2021@comcast.net put suzuki in the subject and I'll send you a copy.

Answered by merlin2021 (expert)
18,145 answers provided

I should know what MIL is, but it escapes me. Was thinking my problem could be the starter draining the battery, or maybe a bad ground.36 pages is a lot, but here's my email you can send it to:
shvlhead68@gmail.com
Thanks, Kerry

Response from shvlhead68
4 questions asked

It's on the way, first thing we do is get that circuit working, then we work on the charging.

Answered by merlin2021 (expert)
18,145 answers provided