1992 Honda Civic VX. Stock D15Z1. No engine or electrical mods. (No CELs, no battery light. Both work on start up.)

About three months ago my alternator or alternator belt began screeching for about 3-5 seconds upon a cold engine start. (Cold engine only, regardless of outside air temp). Two nights ago I noticed when I switched on my headlights the lights would dim and the idle would drop, both temporarily, then recover.

I went by Autozone to get the alternator tested while still installed in the car. They tested the output at the battery at 12.75 volts at idle. I used my HF DMM and it shows 13V at idle.

The same day I removed the alternator and took it to Advanced Auto Parts to have just the alternator tested. They tested independently on their machine three times in a row and every test it showed "good".

I picked up a new OEM belt from Honda, reinstalled the alternator, started the car and measure the volts at 13 again. I then turned on every electrical accessory in the car and it still showed 13 volts.

Alternator is original to the car, 227k miles. Battery was purchased new from Honda in April 2014. I have a Denso reman (210-2013) on order.

Should I replace the alternator?





eH.

 

Your alternator output should be somewhere between 13.6-14.1 volts, anything less than 13.5 volts and you're asking to get stranded somewhere with a dead battery.

I would advise you replace your alternator and install your new belt. Drive for about 300 miles or about a week and readjust the belt again since it will stretch.

 

When you turn the key to ON(II) [engine off], does the charging system warning light in the cluster turn on and stay on?

Unplug the 4P alternator connector. When you turn the key to ON(II) [engine off], what voltage do you read using the alternator housing as ground at the Blk/Yel wire terminal in the 4P alternator connector?

With the engine idling and all electrical accessories off, what voltage do you read using the alternator housing as ground at the alternator terminal nut that secures the large white alternator wire that runs to the hood fuse box?

 

Yes, the battery light stays on with the key at II (ON) engine off.

The other two questions I'll have to get back to you on. Off to work for now.

Which one is the 4P connector?





eH.

 

4P connector:

 

Turns on and stays on.

With my HF DMM, I measured 11 volts.

I reconnected the 4P connector before doing this test. I measured 13 volts. Just to make sure we're on the same page, this large nut is housed under a black rubber boot, correct?

Replace the voltage regulator? (New alternator.)


Thanks!





eH.

 

The alternator is bad.

New alternator? Details.

 

Thanks, Ron. I'll get it pulled tonight to save on the core charge tomorrow.

New (reman'd) alternator is a Denso model 210-2013. I would have liked a new OEM one, but not at $800+. Hoping the reman'd Denso is the next best thing.





eH.

 

You should be plenty fine with your reman alternator.
Do a test after install check the voltage output and don't forget to readjust your belt after 300 miles of driving.

 

No change! I installed the reman'd Denso and both my DMM and Autozone still show a bad alternator.

I'm only getting 13V at idle. I did all three checks again with the exact same results. I also checked the alternator fuse under the dash and checked for continuity between the large nut and the positive terminal of the battery. Everything checks out except the alternator output.

Any suggestions?





eH.

 

I did the troubleshooting guide for the charging system and the result was "replace voltage regulator." This is now with a new reman'd Denso alternator just installed.








eH.

 

The alternator 4P connector has 2 wires that run to the ECU -- AltC (Wht/Yel wire) and AltF (Blu wire). Test both wires for a short or open.

 

A16?

I'll check between C119 and C212, then between C212 and A16.





eH.

 

AltC = A16
AltF = D9

Same for D9.

 

Everything checks out to the ECU.

I broke it down between each connector.

C119 through C103. Both BLU and WHT/YEL

C212 through A16. BLU to PNK

C212 through D9. WHT/YEL

There is continuity all the way through.





eH.

 

What about C119 to each respective ECU pin (A16 and D9)?

Did you test for a short to ground at each pin?

 

Is there a way to do the Alternator FR Signal troubleshooting guide without the test harness?

Should I just try an ECU reset procedure?





eH.

 

The wires on the DMM aren't long enough to go from C119 through to A16 and D9.

How do I test for a ground?





eH.

 

Ground the alternator pins to the thermostat housing and then test for continuity to body ground at each ECU pin.

Unplug the 4P alternator connector and ECU connectors A and D.

Test for continuity to body ground at the two alternator pins and then also at the two ECU pins.

 

You can backprobe the ECU connectors to do the voltage tests without the test harness.

Not sure what this would accomplish.

 

Ok, I don't quite understand the difference between the two, but what I did was use some wire to extend the DMM wires.

I plugged a length of wire into the BLU at 4P and test all the way through to A16. Continuity existed.

Same for WHT/YEL at 4P to D9. Continuity existed.

So how do I check for a short to ground?





eH.

 

Backprobe? Can you explain please?

The ECU reset procedure is what the troubleshooting guide leads to if the is voltage between D9 and A26 and it decrease with headlights and rear defogger.



I'm at a loss on how to test for a short to ground?
EDIT: I think I understand short to ground. If I put the RED lead on the negative battery post and then ground the BLACK wire on say the transmission ground I get a "noise" from the DMM. So I put the RED lead in at D9 and A16 and then grounded the BLACK wire. No "noise".




eH.

 

By back probing, you insert a metal tip onto the back of the connector which will then make contact with the back side of the pin. You can use a paper clip if you don't have a specific back probe kit.


If you want to test for a short to ground, set your DVOM to test for continuity and test from whichever pin/wire you want by touching the pin/wire with one of your leads and a good known ground with the other.

What you are doing/testing is if the wiring harness is making contact(shorted) to ground anywhere in the engine bay. If you have any continuity when touching the test lead to a known good ground, you have a wire shorted.

If you have a shorted wire, easiest thing to do would be to run a new wire as opposed to chasing after the short.

 

Thanks! No shorts on BLU to A16 and WHT/YEL to D9.





eH.

 

According to hondapartsunlimited.com your voltage regulator is part of the alternator, is this correct? Sorry I can't remember.