1994 Suzuki Sidekick • 4 cylinder 4WD Automatic • 137,000 miles

Confirmation of bad PCM. The alternator only charges at an idle (it's been checked and is good), when the battery gets low the battery light on the dash doesn't come on, the check engine light comes on every 100 miles or so, when jumping the terminal to get the cel to flash the code it doesn't flash at all. When the car is at an idle, the battery charges slowly, starting at like 11.4 volts and if you let the car idle long enough (about 10 min) the voltage works its way up to 14.2. With all these symptoms, is the probable cause a bad PCM (power control module)
December 30, 2010.

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.

Dec 30, 2010.
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.


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
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
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.

Dec 30, 2010.
As you can see the regulator is built into the alternator, inspect wires and replace alt if OK.

Dec 30, 2010.
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?

Dec 31, 2010.
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.

Jan 1, 2011.
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

Jan 1, 2011.
It's on the way, first thing we do is get that circuit working, then we work on the charging.

Jan 1, 2011.