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| Voltmeter Reading high (Page 1/1) |
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owenspike
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DEC 31, 07:23 PM
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My voltmeter on my 86 GT started reading high the other day. It is almost always in the red. I'm assuming it's the voltage regulator on my alternator, but I'm also wondering if it could be my gauge. Would I get a check engine light or something if my battery was being overcharged?
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dremu
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DEC 31, 08:37 PM
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Easy to check with an external voltmeter -- heck, even one of those free-to-$2.99 ones from Harbor Freight should give you an idea of what's going on. Really should have one to work on an old car anyway.
-- A
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owenspike
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DEC 31, 08:49 PM
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| quote | Originally posted by dremu:
Easy to check with an external voltmeter -- heck, even one of those free-to-$2.99 ones from Harbor Freight should give you an idea of what's going on. Really should have one to work on an old car anyway.
-- A |
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Will do! Thank you!
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theogre
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DEC 31, 10:12 PM
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Yup, never trust dash gauges.
Check volt at battery. Should see 14-15v w/ engine running.
If too high then wire to alt or alt have problems.
⚠️ Warning: If you see 16 or worse higher shut off engine or high volts can quickly kill many other E-parts.
Take alt to store and let them test. most stores test them free.------------------
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)
The Ogre's Fiero Cave
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owenspike
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JAN 01, 10:49 PM
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| quote | Originally posted by theogre:
Yup, never trust dash gauges.
Check volt at battery. Should see 14-15v w/ engine running.
If too high then wire to alt or alt have problems.
⚠️ Warning: If you see 16 or worse higher shut off engine or high volts can quickly kill many other E-parts.
Take alt to store and let them test. most stores test them free.
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So, at idle it's 15v, but with even a little bit of gas, it goes up to 18. What's most likely the problem?
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Mike in Sydney
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JAN 02, 01:40 AM
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Voltage regulator in the alternator is likely shot. You can replace it but I'd opt for buying a new alternator. You may even want to go to a CS130 unit for more amps if you have an aftermarket sound system or other accessories.
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Mike in Sydney[This message has been edited by Mike in Sydney (edited 12-18-2022).]
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theogre
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JAN 02, 12:50 PM
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creaky78
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DEC 16, 11:43 AM
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Found this post about high reading voltmeter. My '87 voltmeter reads normal, about 14 volts when engine is started, needle pegs about 15 seconds later. Battery voltage remains 14+ volts. Help!
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Dennis LaGrua
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DEC 16, 03:34 PM
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As above check connection and read acoss the battery with a VOM. A reading of 14-14.5V at start cold idle is OK but it should return to around 12-12.V at road load. Should be easy to solve. ------------------
" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "
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theogre
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DEC 16, 07:34 PM
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Dash Volt meter often lies because has many connection to the car that have problems.
Dash Meter Pegs could be meter has loose wiring, bad meter or have real problems... Test at the battery is good.
If has real problems w/ high volts then the ECM often trips codes and CEL turn On.
| quote | Originally posted by Dennis LaGrua:
As above check connection and read acoss the battery with a VOM. A reading of 14-14.5V at start cold idle is OK but it should return to around 12-12.V at road load. Should be easy to solve. |
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not quite
Meter at Battery and many other places in the engine bay...
~ 14 to 15v max w/ Engine Running
engine off and battery @ full charge should read 12.6 to ~ 13.0
Battery charge can vary depending on many things...
Assume a good battery... 2 big items
when the car driven last. a day or two or a week or more matters. (Because ECM etc use some power 24/7.)
how long the engine runs. Takes some time to charge, more so when have a low charge battery.
If you measure volts in the cabin or front of Fiero... often see lower volts because of iffy wiring and grounds on top of small volt drop in every connection.
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