• Hello Guest, welcome to the initial stages of our new platform!
    You can find some additional information about where we are in the process of migrating the board and setting up our new software here

    Thank you for being a part of our community!

New voltage regulator, now won't start?

Google how to do loaded voltage drop tests. Do one on your battery cables and the alt positive and ground cables.
 
Give us some more numbers. Do any of the suggested procedures and post the results. If you shotgun an intermittent problem you'll never know if its fixed. Long distance tow charges are even less fun.
 
Ok, so I went to a different Oreilly's and got another battery test. It also said I had a failed voltage regulator even though I just installed a new one. I then performed a voltage drop-down test. This was the guide I used, it's my first time doing electrical I am definitely a rookie. https://axleaddict.com/auto-repair/Charging-System-Voltage-Drop-Test

Multimeter at 20 DC Volts

Battery reads ~12.8 with car off.

At idle with accessories (no radio or ac) on the battery reads 13.3. At 2k rpm, it also reads 13.3. No real change.

With the positive lead on the positive alternator wire at the terminal and the negative lead on the positive battery post, it reads 0.07 at idle and at 2k rpm. No change with RPMs.

With the positive lead on negative alternator wire at the terminal and negative lead on positive battery post it reads ~3. Again, no change with rpms.

With negative lead on alternator housing and positive lead on the negative battery post, it read 0.15 volts.


Ok, maybe this wasn't that thorough, please let me know what else should be tested or done. My headlight's only turn on when I turn on my high beams and my Kenwood keeps turning on and off. Are these symptoms an alternator not putting out enough current?
 
If your cabin is dying, I would remove and clean all the wires going to the positive junction block on the driver side fender.

Voltage drop test only short sections of a circuit at a time. Like from the alt case, to a clean ground on the block. Don't do it all the way to the battery negative. That is including any voltage drop in your negative cable into the measurement.


It doesn't sound like you have bad cables based on your description of the problem.


Here is a fun test: there may be a yellow/wire by the firewall with just a male spade at the end. Apply 12v here from your favorite source and the starter should fire (DONT DO IT IN GEAR- MANUAL TRANS)

You could also rig your meter inside the car somewhere and monitor voltage. You can monitor charging voltage and also see if the cabin is getting low voltage when you are having the issue.
 
"With the positive lead on the positive alternator wire at the terminal and the negative lead on the positive battery post, it reads 0.07 at idle and at 2k rpm. No change with RPMs."

"With negative lead on alternator housing and positive lead on the negative battery post, it read 0.15 volts."

Excellent! The battery and alternator cables and connections are good.
You should buy a battery monitor for the lighter socket. Find out if the battery is discharging while your driving or after the car is turned off. You are dealing with an intermittent problem.
 
Thanks for the advice! I just ordered one. Not sure if this helps with a diagnosis, but when accelerating hard the headlights may turn on at 5k and the radio will try to turn on as well.
johfraser said:
"With the positive lead on the positive alternator wire at the terminal and the negative lead on the positive battery post, it reads 0.07 at idle and at 2k rpm. No change with RPMs."

"With negative lead on alternator housing and positive lead on the negative battery post, it read 0.15 volts."

Excellent! The battery and alternator cables and connections are good.
You should buy a battery monitor for the lighter socket. Find out if the battery is discharging while your driving or after the car is turned off. You are dealing with an intermittent problem.
Click to expand...
 
DavePolyakov said:
... when accelerating hard the headlights may turn on at 5k and the radio will try to turn on as well.
Click to expand...


Hilarious.

Check for rotted wiring under the driver carpet area for the headlight relay.

Pre-1987 Volvo is notorious for the "biodegradable wiring". It sounds like you are dealing with short circuits in the wiring loom.
 
The voltage drop tests seem good. When you had the alternator tested, and they said bad regulator, did they give you any sort of printout with more details? I think the old Volvo alternators only put out ~13.5 volts versus a more modern ~14.5 volts. I'd expect the alternator tester to account for this, but maybe the "bad regulator" just means that the alternator isn't modern.

Do you know who installed the radio? It sounds like the wiring is intermittent and may have damaged other wiring (e.g. headlights). Cheapo ScotchLok-style crimp on wire taps are notoriously unreliable, and can damage/break the original wire. If your radio was installed with these, or other poor DIY wiring, it may be the source of your battery drain.
61WpNfeKPQL._AC_UL320_.jpg
 
No printout, they attached the tester to the battery and it said "failed voltage regulator". That's what happened at two different Oreilly stores.
Last year when my alternator bracket failed and I was driving home on the freeway unaware my alternator wasn't spinning my Kenwood was the first thing to go, then my headlights. I fixed the bracket right away, but when my Kenwood goes and then my headlights go I assume there is something wrong with my charging system. If I charge my battery overnight I can drive a good distance with my radio and headlights working completely normal. I'm not saying the connections are good, I'm assuming it was not installed professionally. I will take it out tomorrow and inspect the connections on the back.
 
I suggested radio connections due to the radio and headlights turning on under high acceleration - I'm thinking extra vibration (and maybe the engine is leaning over a little more, tugging on some engine compartment harnesses). The radio dropping out when the battery gets low is normal. Maybe they're related?

Edit: I forget, have you measured battery voltage at idle with max. accessories (headlight, radio, wipers, etc.) turned on? If the voltage drops below 12ish volts, then the alternator isn't keeping up with the load and your battery is draining.
 
I really suspect your wiring is fine, and you've just blown some other component of your alternator that shows up as "failed voltage regulator" on their equipment. The lights and radio symptoms would line up nicely with an alternator that is only producing rated voltage at much higher RPM than normal. I've had bad wiring before and it tends to be a lot more random in its failures than you're describing.

You could probably test while parked just by hooking up your meter, tweaking the throttle spool and seeing if voltage goes up and down with RPM.
 
I got my cigarette socket battery monitor today and went for a drive. I think the results were quite alarming.
At idle with all accessories except for the radio which refuses to turn on, 12.5ish. Already knew this with the multimeter though.
At cruising speeds with all accessories it was around 12.8
With no accessories at cruising speeds it was around 13.3-13.5
With even just my high beams it would drop down to 12.9-13.0. If I added on the heater fan it was below 12.8.

Is my alternator toast? Before I started the car it was just around 11.9-12.0 after sitting for two days.
 
^^^ those measurements are a bit on the low side, but at 12.5ish volts, and above, the alternator is keeping up with the load. It is a 35 year old car with an alternator sized for that era.

After parking it, turn the key back on but don't start it and write down the voltage. Next time you go to drive, the voltage before starting should be about the same. If it's dropping significantly day-by-day without running, then something is draining the battery.

You can also try spinning fuse #1 -- fuse #1 goes to the cigarette lighter and, if corroded, the voltage at the lighter can be low.

I'm still suspicious of your radio wiring. The radio should turn on fine at the measured voltages. I'd expect it to drop out if the voltage goes below 10v or maybe 11v, but not at 12+ volts.
 
I will keep track of the voltage. It just seems that there is a correlation between the headlights and the radio. They both started acting strange at the same time. The headlights only turn on when I turn the high-beams on. I need to find the Kenwood keys to remove the stereo, I'll do it soon.
 
DavePolyakov said:
I got my cigarette socket battery monitor today and went for a drive. I think the results were quite alarming.
At idle with all accessories except for the radio which refuses to turn on, 12.5ish. Already knew this with the multimeter though.
At cruising speeds with all accessories it was around 12.8
With no accessories at cruising speeds it was around 13.3-13.5
With even just my high beams it would drop down to 12.9-13.0. If I added on the heater fan it was below 12.8.

Is my alternator toast? Before I started the car it was just around 11.9-12.0 after sitting for two days.
Click to expand...

While not ideal the battery is not going dead in either case. It's an intermittent problem. Continue those checks until you catch the battery being drained in the act.

An additional check you can do is hook your meter up to measure current out of the battery while the car is setting. Disconnect the battery positive cable. Set the meter to measure current on its highest range. Hook the meter between the battery positive terminal and the positive battery cable. Red meter lead to the battery. Then decrease the range until you see a reading. It should be less than 100mA. Leave this hooked up and check it periodically. Turn the meter off between checks so you don't drain its battery.
 
The parasitic drain test^^^^ Yes. You do it on the negative side for safety. I use a special tool (basically just a battery cutoff switch. If you just connect a meter inline without protection it can blow the fuse on your meter. It's a good idea to use a fused jumper lead also to protect your test equipment.



All this being said, it doesn't sound like a discharged battery. Have you tried applying 12v to the starter via the test lead, or to the Blu/yel terminal at the starter when the no crank issue is present!??
 
I did the parasitic test on the negative terminal and my multimeter at 10 amps, it was 0.05
I forgot to mention, the clip on wire on the alternator that connects to the fitting on the block is damaged and disconnects when I'm driving. Is this why I have a relatively low charging voltage? What is that wire?

Oddly enough since I started this post I have not encountered another no-crank condition. I will do the test when, or if it happens again.
 
Seems like you are describing the alternator case ground. That goes from a stud on the alternator to the bracket on the block. If that disconnects you get no charging to the battery.
 
I still can't understand what is going on here.

There are three wires to the alt. The large red wire (alt output), the thin red wire (the exciter) and the blue wire (the ground).


If your ground wire is falling off that is a big problem. You need a good ground wire with corrosion free crimps. I would get a new piece of thick wire, and crimp on two new ring terminals.
 
Last edited:
You must log in or register to reply here.
Back
Top