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I started my car this morning, and the battery, parking brake and brake failure warning bulbs were very dim. I put a meter on the battery and I'm getting 12 volts. Revving up the engine does not help. I have 12.4 volts with the engine off, so I think the battery is fine. According to my Bentley, it tells me to repair wiring or bulb faults before continuing. I don't think this is the problem. I think I have a voltage regulator problem. I removed it and it was full of crud. Cleaned it up and the brushes are about .125. It says to change them below .2. Looking at the schematic, the SRS light and my turn signal indicator lamps should be out. The SRS light is out, but the turn signals work.
Can I just change the brushes on the voltage regulator, or do I have to replace it completely. Am I barking up the right tree? Thanks so much.
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Ed 89 740 176K, 91 240 210K
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posted by
someone claiming to be Al
on
Fri Sep 8 03:39 CST 2006 [ RELATED]
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Have to agree on the brushes and a possible cluster problem also. If you replace the brushes and still have the problem pull the cluster out of the dash and tighten up the screws that hold on the flexible circuit board. Over time they can loosen up and lose the conductivity. The alternator needs a signal from the cluster to tell it to charge. No signal due to a bad connection no charge from the alternator.
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Wow, the cluster detects battery voltage and then the voltage regulator charges the battery. In not that hip on electrical systems but that sounds kinda backa-swards. Oh well, I'll solder some brushes in and see what happens. Thanks for your help.
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Ed 89 740 176K, 91 240 210K
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Actually all the cluster does in this circuit is house the warning lights and some diodes.
When the ignition key reaches Position II, the warning lights should come on, all five (battery, E-brake, oil, brakes and bulb failure, if I recall correctly). So OK, then what makes them turn off? I wondered and asked a helpful Volvo tech.
In Position II, sometimes called "Run" and sometimes called "Bulb Check", battery voltage flows to those warning lights and thence to a ground, and burnt out bulbs don't light.
The oil light grounds in the oil pressure sensor and goes out when oil pressure reaches some minimum pressure. The other lights are grounded through the alternator rotor windings via the brushes.
That small current through the brushes makes a small magnetic field on the rotor so that as the rotor begins to spin, electricity is created. When that happens, the dash lights have positive (+) voltage from the battery, and also (+) voltage from the alternator, so the lights go out.
Thus if the brushes are weak, or the wire connecting cluster to alternator is compromised, charging is affected.
Control of the alternator output is done by the voltage regulator, which is integral in the brushes unit. It senses the level of battery charge and raises the output voltage of the alternator as needed.
I can see it work by watching the voltmeter in my 1988 244GL. Higher voltage immediately after starting, and then dropping to normal after the battery charge used in starting is replaced.
Good Luck with your repair.
Bob
:>)
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As usual, B.C. did a great writeup.
I'll add this - - - somewhere I read that...
Four of those five cluster warning bulbs ground at the alternator and provide the "exciter" voltage to the alt. windings. If all four of those bulbs are burned out then no voltage gets to the windings and the alt won't do it's job. If three are out and one is OK then the alt's function is compromised or iffy. As I recall, if two bulbs are out and two are OK then I think the alternator runs OK.
Anyway, watch those bulbs when you start the car to make sure they all light up. A warning bulb that is burned out is not the way to go.
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DAMHIK: Don't Ask Me How I Know - - - Sven: '89 245. 951 ECU, open-front airbox, E-fan, IPD sways, E-Codes, amber front corner reflectors. 500 mi/week commute. '89 245 #2 (wifemobile). '90 244 (spare, runs).
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GREAT POSTS, Thanks for the info, I think I've misled you though. Those 3 bulbs, Batt, Bk failure and bk wrning are ever ever so dim. I changed the brushes and the lights are the same. I didn't even crank the car up just turned the key to the first position and I have the same results. I'm going to take the cluster out now and check the connections and circuit board. Is there a connector between the cluster and the alternator? Thanks again.
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Ed 89 740 176K, 91 240 210K
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Start the car. If the lights go out then you're okay. System is charging.
The warning lights should be on in key position II before starting to indicate system circuit is there. Dimness before startup could be low battery because you haven't charged in awhile.
--
1980 245 Canadian B21A with SU carb and M46 trans in Brampton, Ont.
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Those three lights stay very dim after the car has been started. Could the alternator just be going bad? I did the T/S per bentley and I'm not sure with terminal I'm on because I can't see any markings with the thing installed but I have a good ground on one, 12V on another and when the key is turned to the first position I get about 7.5V on the last terminal. Not sure if this is good or not? BTW where is that connector between the batt light and the alternator? thanks so much for everyones help
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Ed 89 740 176K, 91 240 210K
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"Those three lights stay very dim after the car has been started."
Let's go back to those lights before starting. Earlier you said they were dim when you turned the Key on. If they aren't as bright as the other lights (e.g., Oil warning), that's wrong and must be analyzed.
Try it again, and if those bulbs (4 actually, counting Bulb Failure) are dim, take the small red wire off and ground it to the block. If the lights get brighter, the problem is in the alternator, regulator, brushed, or blue ground wire.
Test the blue ground wire by grounding the small red to the alternator case. If bulbs get brighter, the blue ground was not making them dim, but those other items are still questionable.
If they stay dim, see what the voltage is on that disconnected red wire. It should be the Battery voltage, feeding thru those bulbs. And yes, there is a connector between the cluster lights and the alternator -- it's gray plastic, on the right/center of the firewall (8-pin but only 4 or 5 wires, including our red one). See stolen pic (ignore arrows).
Here's how those bulbs should work...
• The Battery light (and 3 more) come on with Key On.
• That's due to battery voltage on one side of the bulbs — and ground on the other (from cluster, thru small red wire to the inert alternator D+ terminal).
• The lights go out when the alternator ground path (D+ small red wire) rises to alternator output voltage (B+ big red wire)...
• ...because with voltage now on both sides of the bulbs, there's no current flow — and thus the lights go out.
• If the lights glow when running, the alternator voltage at the D+ red wire must be lower than "battery voltage" (now at Alternator B+ level).
• This difference in "potential" allows a small current flow—and thus the glowing lights.
Most likely cause is at the alternator, assuming the lights are bright with Key On.
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Bruce Young
'93 940-NA (current), 240s (one V8), 140s, 122s, since '63.
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Try it again, and if those bulbs (4 actually, counting Bulb Failure) are dim, take the small red wire off and ground it to the block. If the lights get brighter, the problem is in the alternator, regulator, brushed, or blue ground wire.
Test the blue ground wire by grounding the small red to the alternator case. If bulbs get brighter, the blue ground was not making them dim, but those other items are still questionable
Yep, did them both and the lights are bright. I also ohmed out the little red wire to grd and got 27 ohms, where does this little red wire go to? Does it go up through the bulbs and this is the resistance i'm seeing? I'm thinking that's the way it should be. But please speak up. You've been a great help and I can't thank you enough. Looks like an alternator to me.
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Ed 89 740 176K, 91 240 210K
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The little red wire comes FROM one side of those bulbs (specially connected in parallel before engine runs) to carry the "preexitation current" TO the alternator via that wire, to the D+ terminal.
"Ohming" between ground and the red wire, "upstream" to the bulbs and beyond is anybody's guess. The 27 ohms doesn't tell me anything, I'm afraid.
You said you replaced "the brushes". Is that the brushes alone? Or a Voltage Regulator unit with brushes? If it was just brushes, the problem (lack of good ground path) could be either in the regulator or dirty/worn alternator slip rings.
You could pull the alternator and try cleaning off the slip rings with fine sandpaper while spinning the rotor. I don't know the internals of the VR or alternator well enough to go beyond that.
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Bruce Young
'93 940-NA (current), 240s (one V8), 140s, 122s, since '63.
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The little red wire comes FROM one side of those bulbs (specially connected in parallel before engine runs) to carry the "preexitation current" TO the alternator via that wire, to the D+ terminal.
"Ohming" between ground and the red wire, "upstream" to the bulbs and beyond is anybody's guess. The 27 ohms doesn't tell me anything, I'm afraid.
You said you replaced "the brushes". Is that the brushes alone? Or a Voltage Regulator unit with brushes? If it was just brushes, the problem (lack of good ground path) could be either in the regulator or dirty/worn alternator slip rings.
You could pull the alternator and try cleaning off the slip rings with fine sandpaper while spinning the rotor. I don't know the internals of the VR or alternator well enough to go beyond that
I just replaced the brushes in the voltage regulator, that's it. I used the existing V.R. I cleaned up the contacts and screwed it back on. I'll try cleaning the slip rings and if that doesn't work I'll take the alternator in and have it checked. Thanks ONCE again.
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Ed 89 740 176K, 91 240 210K
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posted by
someone claiming to be Kyle 240
on
Sat Sep 16 14:16 CST 2006 [ RELATED]
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With the regulator assembly out, you could sneak your ohmmeter probes into the slip rings and make sure the rotor winding is not open. I've had one Bosch die like that after a lead was ripped by something the alternator took on probably as a result of running without a belly cover. Should be around 4 ohms IIRC. Was a '91 by the way...
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Are you saying going across both slip rings and I should have 4 ohms? It's open, so I guess that's my problem.
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Ed 89 740 176K, 91 240 210K
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posted by
someone claiming to be Kyle 240
on
Mon Sep 18 12:19 CST 2006 [ RELATED]
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That first one is just how mine looked except there was less of the winding to grab. Did you try to repair it like I did? Used a piece of #16 wire from a florescent ballast. Still running fine.
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Sorry it's taken so long to give you an update. It was the Alt. Got a rebuilt, hooked the wires up and all the lights came on, bolted it in - life is good. Thanks to everyone for all your help.
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Ed 89 740 176K, 91 240 210K
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The lights are very dim BEFORE and AFTER starting. I just read your post so I can't tell you anything else at this point but I will give you an update soon unless you have any other ideas now that you have the full story. Thanks
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Ed 89 740 176K, 91 240 210K
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So do you think it's the brushes? I was leaning that way but wanted another opinion.
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Ed 89 740 176K, 91 240 210K
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I find that the brushes available from Volvo(about $4)are easier to work with than the ones I have found in aftermarket. The Volvo brushes have nice solid leads to "thread" the woven wire through the hole that eventually get soldered and then the leads are snipped off.
I also find it easier to drill out the old solder joint with a 1/16" drill; and to make drilling easier I file the old solder joint flat to find the center (image below)
Pull the brushes in far enough to stay in the holder when under pressure from the springs. Bend over the lead to hold in position and solder in place simply by filling the hole.
Tip the assembly to reinstall it and push/hold it in position while installing the screws.
Randy
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Great instructions and pics. Thank you.
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Ed 89 740 176K, 91 240 210K
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BTW I forgot to include the Volvo part number for the brushes: 1362710
Randy
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Yes you can replace the brushes but you will need to solder them on. Dan
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