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240 Need help with some sort of electrical issue please

Elvolvito

Member
Joined
Sep 29, 2020
Location
Florida
Alright, so my ?88 244 is having an electrical issue I believe. About a month ago, the alt belts started squealing as well as all the lights in the car occasionally dimming. This problem persisted for about 2 weeks till I took it to the local euro mechanic in my area & he let me know that my alternator was overcharging, & he recommended getting a new alt & installing a new battery as well since all that overcharging fried up my battery. Fast forward to now, I?ve installed a brand new alt, as well as a new battery & it?s been riding completely solid for about a week. However, the belts started shrieking again just now & the powers giving signs of going dim again. Now I have a very good suspect in mind for what?s causing this. Before all of this ever started occurring, I had just installed 2 new front speakers in the car. (https://www.bestbuy.com/site/pionee...l-speakers-pair-black/6065206.p?skuId=6065206). I never really did any research on speakers for my Volvo before purchasing them & I believe that they may be sucking too much juice out of my alternator & that?s causing it to overcharge? What do you guys think? I even just uninstalled them off the wires & the car actually does seem to be doing better. I just want to be sure that it?s the speakers. Thank you.
 
All the lights in my ‘80 flutter and I have no sound system, it’s just a weak charging system or bad grounds. You can try swapping bulbs for LEDs and lower your draw on the alt if you don’t want to install a higher amp alt.
 
I am constantly chasing electrical issues in my car and so far 99% of the time it’s just been a bad ground or corroded/dirty connection. Just slowly making my way through all the connectors in the car and either cleaning or replacing
 
My belts & pulleys are good according to the mechanic & myself after a thorough inspection. Okay the issue seems to be coming from the small D+ terminal on the alt. Another thing I’ve noticed is that the battery light (alt light) on the dash doesn’t flash whenever I go to turn on the car & whenever I flick the key to the first position.
 
If the charging system has a bad charging light circuit. You can get weird flashing and dimming of the lights. Especially the cluster. Time to troubleshoot the charge light circuit. Start by grounding the charge light wire to the alternator case. Turn on the key. You should have the dash light on. If not on use another ground like the valve cover. If it's still not on you need to test the wiring or replace a bad bulb. If the light comes on with another ground. You need to repair the ground wire for the alternator case.
 
It highly unlikely that a new radio could have caused battery/alternator problems, especially if the new radio is fused correctly. I'd be searching for a damaged +12volt/+Alt wire that's starting to short to ground. The alternator + wire wraps around the front of the block, by the crank pulley, then to the started. It can suffer from age/heat/oil/road debris damage.

Get a $10 cigarette lighter voltage gauge (amazon: usb car charger volt meter) to monitor voltage while driving. If you want to fast charge your phone, get the fancier $15 iphone rated version. On an old Volvo, voltage should be ~13.5 to ~14volts, and maybe a bit less when hot. On more modern cars, maybe ~14.5v. 12ish volts, or lower, means you're draining the battery and will eventually have problems starting.
 
So I just did a voltage test on the battery on the battery, it’s 12.30 with the car off & it drops down to around 12.00 when I start the car, meaning the alternator isn’t charging the battery whatsoever.
 
I did just suggest to test the charge light circuit. Your alternator won't charge without it working. Unless you rev the engine to around 4k rpms. Then it might self excite.
 
I did just suggest to test the charge light circuit. Your alternator won't charge without it working. Unless you rev the engine to around 4k rpms. Then it might self excite.

Just did the test you suggested & the dash light didn?t turn on whatsoever.
 
So you either have wiring issues typically where the wires pass through the alternator bracket and under the crankshaft pulley or the bulb in the dash is bad.
 
That is correct. Without the exciter circuit aka charging light. The alternator won't charge. The Bosch alternator can self excite if you rev them high enough but you can't count on that working every time.
 
Quick test for the system- turn key on light should come on.start engine light should go out. No glowing or flicking.turn key off light should come on as engine is stopping. System must pass all three test or you might be walking.
 
Definitely fix/test the charging light circuit. Verify the alternator case is grounded to the chassis and engine block.
If you really want to know how much current you are drawing from the alternator use a clamp on ammeter. The more current you draw from the alternator the more torque it takes to turn it. You don't get that energy for free.
 
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