Question about 1986 Pontiac Fiero

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86 fiero voltage spike

Had a voltage spike, thought it was the alternator. Thought wrong. What could the voltage spike be from?

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Check for bad/corroded ground wires/straps, going to the body and to the motor. 

Posted on Jan 10, 2009

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2000 dodge dakotacha 3.9l trys to start with no key in it but will start with key in it. changed switch and relay no change power still going to solonoid ?


Just a second thought. With the starter relay unplugged, You can use a testlight and check for voltage at terminal 86, if voltage with key out, I agree with Arnie, something wrong with switch or wiring connector or that circuit is shorted to voltage.
I didn't kno litre size of engine or if it mattered?

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Dec 23, 2015 | 2000 Dodge Dakota Quad Cab

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I have a 2010 IQ 600 widetrack, blown 3 computers in the last 2 years, getting expensive, any suggestions on what could be wrong


have the output voltage of the alternator checked and have the voltage of the regulator checked
Maximum is 14.5-14.8 volts dc
high than required voltages will damage an ECM
spikes from jump starts will burn an ECM
Spikes from dirty / loose ground wires will burn ECM

Dec 01, 2015 | Cars & Trucks

1 Answer

Fusible link between the alternator and battery ?


Check for battery voltage at the alternator post with the car off
should be batt. voltage there. I thought the big red wire went straight
to the battery. Fuse links are all down at the starter,might be worth checking. If there is not battery voltage at the alt. you could run a wire from there to the battery but that doesn't explain what went wrong in the first place

Feb 11, 2013 | Oldsmobile Cutlass Ciera Cars & Trucks

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Electrical: I have a 2000 Dodge Grand Caravan and the battery light came on . So i hooked up my tester on the alternator and got a low output, than disconnected the negative terminal while the engine


My 2000 Caravan developed this problem after our hard winter so I searched and found that tapping the alternator might reveal that the brushes were intermittent. Sure enough, a slight tap caused the charging voltage to come on at around 14 Volts. A new brush assembly was under $10 on eBay and after finally getting the alternator out and the brushes replaced, re-installed all was well!

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Feb 21, 2012 | 2000 Dodge Grand Caravan

1 Answer

My 1986 Fiero GT has a severe drop in electrical power when the headlights are on, or the a/c on high, with both on and the radio the car misfires and the volt gauge goes to 9volts. I have replaced the alt...


The problem is not with the + (positive) side of things. The problem is you have bad grounds.
With the car running, grab a voltmeter and check the voltage at the battery terminals. If it is above 12 volts then the alternator is charging, but that is no guarantee that the voltage is getting where it is supposed to.
Fieros don't have solder joints. When the harness needs to have a wire break-out, they just used a metal crimp to electrically connect it to the circuit. They don't conduct well especially over time as they're two different metals in contact with each other flowing electricity.
Anyways, try finding ground wires that are disconnected and not giving the electricity the path it needs to the chassis. Even though the skin of your car is plastic & fiberglass, the skeleton is steel and conducts electricity.
I had to go through my '86 GT and add a dedicated ground just for the front compartment accessories, then I went through the harness and actually soldered my connections. Its nice being able to see at night!

Jul 20, 2011 | 1986 Pontiac Fiero

1 Answer

Have changed out the Alternator and battery with new ones. Battery will still not stay charged. Thought it may be a Voltage Regulator issue is that the only other thing it could be?


MAKE SURE YOUR BATTERY CABLES ARE CLEAN AND TIGHT.MAKE SURE YOU ARE GETTING GOOD GROUND AT NEGATIVE BATTERY CABLE.IF BATTERY CABLES VERY OLD REPLACE THEM.IF ALL IS GOOD ALTERNATOR HAS LOOSE B+ WIRE AND FIELD WIRES CONNECTIONS MAKE SURE NONE OF WIRES DAMAGED AND ALTERNATOR DRIVE BELT NOT LOOSE SLIPPING.IF ALL GOOD YOUR ALTERNATOR HAS THE WRONG AMP AMPS TOO LOW HAVE WRONG ALTERNATOR. OR YOU HAVE FAULTY ALTERNATOR.

Aug 22, 2010 | GMC Safari Cars & Trucks

1 Answer

How to change struts on 86 pontiac fiero


Jack up car.
Remove tires on back.
Remove Nut on top of each strut, located inside engine hatch.
Remove lower bolts from spindle.
Remove strut.
Use spring compressor to remove springs.
Reverse procedure to replace.

Apr 30, 2010 | 1986 Pontiac Fiero

1 Answer

My 86 Fiero SE clutch master cylinder is weeping


Replace it. Not a difficult job. Be careful the bracket on the V6 4spd. isn't strong so don't break it while loosening the slave cylinder retaining nuts.

Good luck,

Rebel Faggioli

Dec 30, 2009 | 1986 Pontiac Fiero

1 Answer

86 fiero thermostat and exhaust problem


The thermostat is held in place by a rubber seal around it and the access cap. One of those is allowing the thermostat to move freely.

The bright red manifolds indicate that combustion is occurring in the exhaust manifold. This is usually a retarded ignition timing issue. Check your timing and see if that helps the hesitation at idle.

Good luck,

Rebel Faggioli

Dec 20, 2008 | 1986 Pontiac Fiero

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