Voltage question (Page 2/3)
1985 Fiero GT OCT 12, 06:13 AM
Yes, I have read your articles, but like I said, the wiring on this car is quite good, I'm sure it is possible that there are some problems, could very well be the sensor for the alternator, but what I have seen indicates that the overall wiring is quite good, but from my symptoms if you can point me at a specific location to remove and clean connections and test voltages to rule out a specific wiring issue, that would help, even if it is wiring, it will be something intermittent, although it is completely random, it can happen when I am driving at 80 on a somewhat bumpy road and it can happen while sitting still and idling, and anything in between, if it were a physical wiring issue I would expect it to have some correlation to a physical cause, either a specific kind of bump, specific rpm, specific temperature, specific speed, etc. The symptoms are like the alternator is being turned off by something, but what is puzzling is why it always turns back on, and why it is only off for a few minutes at a time, seemingly randomly. Thanks.
Vintage-Nut OCT 12, 09:13 AM
BTW - I replaced my factory '88 V6 CS130 Generator/Alternator recently as it died after 136k miles.

Because the difficulty (time) to replace the part, I thought it's wiser to spend more for a higher quality part than choosing the "cheapest option".

ACDELCO GOLD (PROFESSIONAL) 3351010
https://www.rockauto.com/en...49208&pt=2412&jsn=10

Of course, you can always go 'cheap' but my time is more valuable.....

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Original Owner of a Silver '88 GT
Under 'Production Refurbishment' @ 136k Miles

lou_dias OCT 12, 09:27 AM
Get Rodney's power pulley kit along with his plug adapter and go with the '88 alternator and never look back...
theogre OCT 12, 11:02 AM

quote
Originally posted by 1985 Fiero GT:
Yes, I have read your articles, but like I said, the wiring on this car is quite good, I'm sure it is possible that there are some problems, could very well be the sensor for the alternator, but what I have seen indicates that the overall wiring is quite good, but from my symptoms if you can point me at a specific location to remove and clean connections and test voltages to rule out a specific wiring issue, that would help, even if it is wiring, it will be something intermittent, although it is completely random, it can happen when I am driving at 80 on a somewhat bumpy road and it can happen while sitting still and idling, and anything in between, if it were a physical wiring issue I would expect it to have some correlation to a physical cause, either a specific kind of bump, specific rpm, specific temperature, specific speed, etc. The symptoms are like the alternator is being turned off by something, but what is puzzling is why it always turns back on, and why it is only off for a few minutes at a time, seemingly randomly. Thanks.

You can upgrade to CS & Still have same problem because wasn't a bad SI.

Iffy "Grounds" can affect engine running because not all are Grounds like Tan "Ground" is 1 side of "1 wire" O2 sensor for ECM.

Iffy "Battery" light & related parts in the dash, Iffy Alt Side Plug, & just wire for that light will cause problems like that. Other wiring problems can do that too.

Don't go but "how they look." Disconnect, Clean, & lube w/ Brake or Silicone Grease all "grounds" bolted to engine, wires to Alt & + Box under C500.
As you check, look/feel wires at ends... Water damage under insulation can make wires swell or even break there & feel way different then good crimp ends.

See cave, Alt Sense telling what the side plug does.

I would even carefully "unbolt" & unplug C500 & plug it in a few times. Don't remove the Bulb Grease that "waterproof" it. That can make the connections to get better metal to metal as wipe away/thru "rust" in them like The Battery Light goes thru.

Cleaning Engine Grounds often needs "Dremell" w/ wire wheel/disk, cup, etc to clean the "stud" many attach to. Many "Dremell" kits steel wire wheel but can buy cups & other shapes. Don't need SS or Brass wheels for this job. That often makes quick work of cleaning the studs even if can reach all of it. Don't run "dremell" @ max speed w/ any wire brush. Running over rev just ruins them & fly off wires often find your skin, worse Eyes. Don't need the threads total clean but bolt head face @ base should be bright metal.

I recently had "Ground" problems because missed cleaning 1 Stud on Trans Bell.... The Ends are good & lubed from old engine but missed cleaning that stud cause weird Codes for ECM & Ignition problems because DIS Power Ground uses same stud. And this happened several years after replacing the engine. I may have clean that stud but forgot to grease it to keep out "water."

Go buy Permatex Green Brake Grease. Won't run or dry like most Silicone grease in the engine bay.
1985 Fiero GT OCT 12, 11:11 AM
Ok, I will try to investigate wiring more, winter is close upon me so I will add wire cleaning to the list of winter projects!
Frenchrafe OCT 12, 11:22 AM
What Ogre says about grounds is so true.
However, I went up to your original message and I think that the alternator is not pushing out what it should?
Some of the other replies concerning the state of the alternator and/or it's regulator should be looked into.
An alternator here in europe will push out 14.2V.
Anything less, like your 13.6V would seem a little low?
Even at idle, it should try to stay close to 14V (13.8, 13.9, etc...)
Droping off to battery voltage at idle or when at low speeds is in my opinon a bad sign.

------------------
"Turbo Slug" - '87 Fiero GT. 3800 turbo. - The fastest Fiero in France! @turboslugfiero
https://youtu.be/hUzOAeyWLfM

1985 Fiero GT OCT 12, 11:28 AM
Yes it hits 14 anything very rarely, and only for a few seconds before it goes back to about 13.6, like I said it is the lowest spec alternator a v6 could come with, 66 amps, so it could be that it can't generate enough volts. I know engine off battery charge is around 12v, so it is definitely doing something, maybe not enough though.
Frenchrafe OCT 12, 12:42 PM
Well that's not good.
Try finding a cheap one on RockAuto, Ebay, etc...
I changed my alternator a couple of months ago with a RockAuto special clearance sale. Only cost arround 30โ‚ฌ + shipping.
Works fine๐Ÿ‘๐Ÿ˜‰

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"Turbo Slug" - '87 Fiero GT. 3800 turbo. - The fastest Fiero in France! @turboslugfiero
https://youtu.be/hUzOAeyWLfM

theogre OCT 12, 12:49 PM

quote
Originally posted by Frenchrafe:

What Ogre says about grounds is so true.
However, I went up to your original message and I think that the alternator is not pushing out what it should?
Some of the other replies concerning the state of the alternator and/or it's regulator should be looked into.
An alternator here in europe will push out 14.2V.
Anything less, like your 13.6V would seem a little low?
Even at idle, it should try to stay close to 14V (13.8, 13.9, etc...)
Droping off to battery voltage at idle or when at low speeds is in my opinon a bad sign.

Depends exactly where tested...
@ the alt or battery should be nearly same volts.
But The rest of car... Anything Have Many Connections & each one add a voltage drop. Worse Often have wiring problems on top of that.

So Volts across say HL Bulb is Often 1 to 3 volts < Volts @ the battery.

Even when Alt is 100% Good, Anything Wrong w/ Sense Wiring & Side Plug means Volts are higher or lower then Spec.
Is Why GM for about 85 model year shortened the sense wire to jumps directly to alt output. & all models not just Fiero.

When have SI or others w/ crap plugs, Just Touching the plug can make volts to change or shut off.
CS w/ Locking Metripack Plug doesn't have that problem because can't move & is Weather Resistant to keep out "water."
Frenchrafe OCT 12, 01:07 PM
Yeah, goes without saying; voltage tested at the battery connections.
Anywhere else, there could be voltage drops.

------------------
"Turbo Slug" - '87 Fiero GT. 3800 turbo. - The fastest Fiero in France! @turboslugfiero
https://youtu.be/hUzOAeyWLfM