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Topic: What in the ....?????? Low voltage reading, yet full battery and alternator working. (Read 19654 times) previous topic - next topic

What in the ....?????? Low voltage reading, yet full battery and alternator working.

Reply #15
The 90 amp unit from the MarkVII is external, but in 87, he'll have a 60 amp internal regulator.  Junk in my opinion.  Even with everything stock, 60 amps in comically inadequate.

What in the ....?????? Low voltage reading, yet full battery and alternator working.

Reply #16
Just "chimeing" in, My 88 with the 3G has 5 bars, drops to 4 every time I turn the AC/fans on.  Never lower.
Mike

What in the ....?????? Low voltage reading, yet full battery and alternator working.

Reply #17
Quote from: mcb82gt;434830
Just "chimeing" in, My 88 with the 3G has 5 bars, drops to 4 every time I turn the AC/fans on.  Never lower.

My Thunderbird with the 2G does the exact same thing.
88 Thunderbird LX: 306, Edelbrock Performer heads, Comp 266HR cam, Edelbrock Performer RPM intake, bunch of other stuff.

What in the ....?????? Low voltage reading, yet full battery and alternator working.

Reply #18
Quote from: ZondaC12;434813
Running, the car should be charging somewhere between 13 and 14.4 volts.
For this reason the digital dash is awesome, if for nothing else. I was rounding an on-ramp in the red car last month and suddenly heard a beeeeep and noticed it switched to oil pressure. I immediately went into a panic mode, but at the same time noticed that the normal number of bars (3 or 4 I think?) were present. Toggled through elec/temp/oil again, no change. Pulled over anyway, shut 'er down. Not full but not real low either. Must have momentarily sloshed from the pickup. You always tell yourself you'll keep an eye on the gauges, but you almost never hear that unique beep, so when you do its an "attention-getter"! (say that in a Jackie Gleason southern voice ;) )

I've tested the car while running before with this very alternator right after I put it in.  It was either a very high 13 or low 14.  And yes, I'm a huge fan of my Studio 54 dash!

Quote from: softtouch;434820
You may want to make a couple of quick checks with your volt meter to confirm the alternator is probably bad.
The voltage checks will be on the alternator connectors. You can unplug them if that is easier for the probe type you have.
1. With the key off, check for battery voltage on the BK/O wires to the Alt B+ . Look for overheating damage to this connector.
2. With the key off, check for battery voltage on the Y/W wire to the regulator A terminal.
3. With the key in run (don't start) check for battery voltage on the LG/R (may be LG/Y) wire to the regulator I terminal.

You need all of the above voltages for the Alt work.

I will check those this afternoon.  Thank you softtouch, you always come through ;)

Quote from: Aerocoupe;434824
Since your car has an external voltage regulator so you might want to grab that and take it to get checked along with your alt.  Just because the alt is somewhat new does not mean its good to go.  We have all been down that road a couple of times.

If its the alt then hopefully its still under warranty and if it is the regulator then that is cheap enough.  I too would suggest going to the 3G alt but if you are 100% stock then I don't know if it is worth it.  I have waaay too much aftermarket electrical components on both of my cars so I made the swap to a 3G years ago.

Darren

Darren; this is exactly why I never swapped/upgraded earlier. 

I'm contemplating 2 options:
1. Full out 130 3g alternator conversion kit replete with secondary power wire:  http://www.latemodelrestoration.com/item/SVE-17046K2/Mustang-SVE-130-Amp-Alternator-Upgrade-87-93-50L

2. 95 amp 3g alternator:  http://www.latemodelrestoration.com/item/PA-16146B1/87-93-Mustang-50L-302--95-Amp-Satin-Finished-Replacement-Alternator

I like the fact that the 130 has the secondary power wire in the kit I linked to.  It's supposedly not necessary, but RECOMMENDED.  It never hurts to be safer and for the extra $40 oer the 130 amp kit without it, I'll take the peace of mind.  For me 130 amps is a bit overkill though.  Would it be a feasible to run the 95 amp unit in combination with the secondary power wire?  It's sold separately.  See here: http://www.latemodelrestoration.com/item/PA-9902/Mustang-3g-alternator-Premium-4-Gauge-Power-Wire-Kit-W-Noise-Suppression

The wire WITHOUT noise suppression is 15 bucks less. 

Looks as if the 130 kit would be a better value than purchasing the 95 amp alternator and the power wire separate, ESPECIALLY if the wire included with the 130 amp kit is in fact the noise suppression variety.....
I'll test further and see what happens.  Had to work the 3PM-11PM shift all weekend.  I can dig into this after 1PM. 

Stay tuned  ;)
-- 05 Mustang GT-Whipplecharged !!
--87 5.0 Trick Flow Heads & Intake - Custom Cam - Many other goodies...3100Lbs...Low12's!

What in the ....?????? Low voltage reading, yet full battery and alternator working.

Reply #19
Yeah, 3G is the way to go. Especially if you have a 2G with that py connector that overheats and causes problems.
Long live the 4-eyes!  - '83 Tbird Turbo - '85 Marquis LTS - '86 LTD Wagon-  '81 Granada GL 2dr

What in the ....?????? Low voltage reading, yet full battery and alternator working.

Reply #20
Quote from: softtouch;434820
You may want to make a couple of quick checks with your volt meter to confirm the alternator is probably bad.
The voltage checks will be on the alternator connectors. You can unplug them if that is easier for the probe type you have.
1. With the key off, check for battery voltage on the BK/O wires to the Alt B+ . Look for overheating damage to this connector.
2. With the key off, check for battery voltage on the Y/W wire to the regulator A terminal.
3. With the key in run (don't start) check for battery voltage on the LG/R (may be LG/Y) wire to the regulator I terminal.

You need all of the above voltages for the Alt work.


*SIGH*

......
Here's what I got:

Battery Voltage:  12.10
Test #1:  0
Test #2:  0
Test #3:  1.169

Tests #1 & #2 were performed with the connectors plugged and unplugged just for confirmation.  Time to dig deeper it looks like.  It looks like a good thing I picked up that wiring harness.

*EDIT*

Started car:  11.74 across the battery at idle.  Kick it up to 1500:  11.74
Back to idle and turn on headlamps, radio, heat, defroster, and left hand turn signal.  Let run for a minute in this configuration:  11.40
Turn everything off and let engine run @ idle:  11.74......

What?!
-- 05 Mustang GT-Whipplecharged !!
--87 5.0 Trick Flow Heads & Intake - Custom Cam - Many other goodies...3100Lbs...Low12's!

What in the ....?????? Low voltage reading, yet full battery and alternator working.

Reply #21
Found my problem.  Blown fusible link near the starter solenoid.  Now I have to look up what size it is....  IIRC it's 16 guage....
-- 05 Mustang GT-Whipplecharged !!
--87 5.0 Trick Flow Heads & Intake - Custom Cam - Many other goodies...3100Lbs...Low12's!

What in the ....?????? Low voltage reading, yet full battery and alternator working.

Reply #22
Yes it is a black 16 gauge.
This usually happens if you hook-up jumper cables backwards.

What in the ....?????? Low voltage reading, yet full battery and alternator working.

Reply #23
Check thr condition of your two yellow charge cables right after your plug.

i used a new connector and crimped and heatshrunk mine installed maybe a year ago. one of the charge cables was completely off and the other one broke just touching it.

go get a tarus alt, buy some cheap 6-8 guage jumper cables for wire and a $20 fuse kit for a 150amp stereo, or breaker if you prefer. done for less then $100 and have 80 amps idle  and 130-160
Quote from: jcassity
I honestly dont think you could exceed the cost of a new car buy installing new *stock* parts everywhere in your coug our tbird. Its just plain impossible. You could revamp the entire drivetrain/engine/suspenstion and still come out ahead.
Hooligans! 
1988 Crown Vic wagon. 120K California car. Wifes grocery getter. (junked)
1987 Ford Thunderbird LX. 5.0. s.o., sn-95 t-5 and an f-150 clutch. Driven daily and going strong.
1986 cougar.
lilsammywasapunkrocker@yahoo.com

What in the ....?????? Low voltage reading, yet full battery and alternator working.

Reply #24
Replaced the fusible link:  13.8 volts at 1500 RPM

.. The link still gets hot. I started digging... Found this.

The yellow and black wires go back into the single 16 gauge fusible link that I replaced.  The green wire with red strip goes to the voltage regulator.
The connection sits right underneath the battery. The red wire dead heads into it with nothing going forward to the charging and light harness.....What the hell is that one for?








 
And yes, I know I gotta clean under there.  The repaint caused most of the grime.  I haven't head a chance to pull out the wiring to start this until now.
-- 05 Mustang GT-Whipplecharged !!
--87 5.0 Trick Flow Heads & Intake - Custom Cam - Many other goodies...3100Lbs...Low12's!

What in the ....?????? Low voltage reading, yet full battery and alternator working.

Reply #25
That connector is under the battery? I have no idea where that goes but I can take a look on my car tomorrow if you want.
88 Thunderbird LX: 306, Edelbrock Performer heads, Comp 266HR cam, Edelbrock Performer RPM intake, bunch of other stuff.

What in the ....?????? Low voltage reading, yet full battery and alternator working.

Reply #26
No idea. if i get bored i might pull up an 87 evmt and dig into it. ill probably check my bird tomorrow when i pull the engine as well to see if it goes anywhere.

glad you got the fuseable link all figured out at least.
Quote from: jcassity
I honestly dont think you could exceed the cost of a new car buy installing new *stock* parts everywhere in your coug our tbird. Its just plain impossible. You could revamp the entire drivetrain/engine/suspenstion and still come out ahead.
Hooligans! 
1988 Crown Vic wagon. 120K California car. Wifes grocery getter. (junked)
1987 Ford Thunderbird LX. 5.0. s.o., sn-95 t-5 and an f-150 clutch. Driven daily and going strong.
1986 cougar.
lilsammywasapunkrocker@yahoo.com

What in the ....?????? Low voltage reading, yet full battery and alternator working.

Reply #27
http://www.coolcats.net/library/fusepanel.html

shows 3 16 guage fuseable links.

lamp feed, ignition feed or rear window defroster.

my moneys on rear window defroster assuming you don't have one, but just a guess.
Quote from: jcassity
I honestly dont think you could exceed the cost of a new car buy installing new *stock* parts everywhere in your coug our tbird. Its just plain impossible. You could revamp the entire drivetrain/engine/suspenstion and still come out ahead.
Hooligans! 
1988 Crown Vic wagon. 120K California car. Wifes grocery getter. (junked)
1987 Ford Thunderbird LX. 5.0. s.o., sn-95 t-5 and an f-150 clutch. Driven daily and going strong.
1986 cougar.
lilsammywasapunkrocker@yahoo.com

What in the ....?????? Low voltage reading, yet full battery and alternator working.

Reply #28
The link is for the ignition circuit. I have a rear defroster and it works without issue.  The black wire with orange strip in that connect makes a straight run to the alternator, it's the power feed.  That is the wire that needs to be upgraded/supplemented when upgrading to a 3g alternator.  The yellow goes I don't know where yet. 


Also; I have another bundle of wires that has been in the car since I purchased it in 1998.  It's 5 wires.  4 of them are clipped.  The last goes to a 2 inch by 1 inch box mounted by the battery.  This box has another wire coming out of it that grounds to the frame.  All small stuff; 16-18 gauge.  I never paid it much mind and chalked it up to a factory alarm system that was removed.  The wires go to their own dedicated hole in the firewall with what APPEARS to be a factory style rubber grommet.  I'll get pictures of that later.  I'd like to remove it completely.

Ahhh, the '80's  - where wiring amounts grew and they stuck the new ones wherever with zero care......
-- 05 Mustang GT-Whipplecharged !!
--87 5.0 Trick Flow Heads & Intake - Custom Cam - Many other goodies...3100Lbs...Low12's!

What in the ....?????? Low voltage reading, yet full battery and alternator working.

Reply #29
Quote from: V8Demon;434894
Replaced the fusible link:  13.8 volts at 1500 RPM

.. The link still gets hot. I started digging... Found this.

The yellow and black wires go back into the single 16 gauge fusible link that I replaced.  The green wire with red strip goes to the voltage regulator.
The connection sits right underneath the battery. The red wire dead heads into it with nothing going forward to the charging and light harness.....What the hell is that one for?








 
And yes, I know I gotta clean under there.  The repaint caused most of the grime.  I haven't head a chance to pull out the wiring to start this until now.

This is connector C403 in the following diagram. The red wire is not used on 5.0, only used on 3.8.