electrical issues
Printed From: West Coast Fieros
Category: Technical Topics Forum
Forum Name: Technical Questions and Discussions
Forum Description: Got a technical question about your fiero? ask it here.
URL: http://www.westcoastfieros.com/forum/forum_posts.asp?TID=1747
Printed Date: 24 April 2025 at 6:26am
Software Version: Web Wiz Forums 12.01 - http://www.webwizforums.com
Topic: electrical issues
Posted By: mxracer208
Subject: electrical issues
Date Posted: 23 February 2010 at 9:30am
| I have a few electrical issues with my 86 GT and I was wondering if I anyone could help. My speedometer doesn't work, the temperature guage doesn't work and the tachometer is way off. (Idle is 3000) Also the turn signals blow a fuse after about 30 seconds. Any help would be great. |
Replies:
Posted By: Patrick
Date Posted: 23 February 2010 at 9:58am
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If you're not familiar with http://www.fiero.nl/cgi-bin/fiero/Ultimate.cgi?action=intro - Pennock's Fiero Forum , you better add it to your "Favorite" list right now. There is a whole lot more traffic through that site than here, and there is a HUGE database of ten years worth of posts covering anything and everything to do with fixing Fieros.
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Posted By: CFoss
Date Posted: 23 February 2010 at 7:21pm
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Would a schematic help (Are you electrically inclined)? The speedo has an internal buffer which requires +12 and ground and the signal from the vehicle speed sensor to work (VSS). The Tach needs a signal from the distributor and +12 and ground to work. I think the temp guage needs +12 and ground and a sender wire to work. I wonder if the fuse you are blowing also feeds the guages??? Anyone know...I don't have that part of the schem handy... Chay ------------- 86 SE 3.4 |
Posted By: mxracer208
Date Posted: 23 February 2010 at 7:56pm
| thanks for the help |
Posted By: ARTIC-1
Date Posted: 23 February 2010 at 8:14pm
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i have what you need,cant post it because the file is 300k E/mail me an ill
send it to you,hope this help. ------------- SNOW MAN 87-GT/AUTO-2.8_ WHITE 88-TTop/ Duke-2.5. RED |
Posted By: Patrick
Date Posted: 23 February 2010 at 8:23pm
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From http://www.westcoastfieros.com/forum/forum_posts.asp?TID=1193&PN=1 - Here ... http://www.captfiero.com/paperbased/Wiring%20Scans/1986GTSchematics.pdf - 1986 System Wiring Diagrams Pontiac - Fiero
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Posted By: Matt
Date Posted: 24 February 2010 at 12:37am
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Your speedo doesn't work because the drive gear in your transaxel is gone. (chewed up into bits inside the transaxel, but mostly drained out now) Your tach has a loose/cracked wire near the distributor. Just jiggle the main harness around and the tach will come to life. Get a VOM and start checking through your harness for cracked wires.  Trust me I know... *CFoss is an excellent resource here*And temp gauge, define way off? What temp is it showing? Last time I drove it.. almost a year go, the thermostat was fine and temp was great. Have no idea about turn signals, they worked fine a year go. Never owned the car but worked on it and knew previous owner. Good Luck! ------------- I wanna go fast. |
Posted By: CFoss
Date Posted: 24 February 2010 at 11:41am
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Is it the transaxle side gear or the vss side gear...he could just get a new vss, no? There is an easy check for the guage...when you turn on the keys to 'test' the guage should max out. This is because in the ignition switch the test position shorts out the sender lead and that causes full deflection. If this works then... take this one step further..move the keys to the run position and locate the sender on the engine, pull off the wire and short it out...full deflection? If not, the problem is in the wiring between the sender and the guage. If it does go full deflection, get a new sender. With the tach, it needs to be checked out. Either it's a dist connection like Matt says, or the 'tach filter' is toast, or there is a connection problem with +12 or ground in the instrument panel. It's probably the dist connector, as they are a known weak spot. To check this, get an oscilliscope to see the signal, or use a voltmeter capable of HZ detection. If I was on the mainland I'd do it for you, but alas I'm on the beautiful island enjoying the sunshine. Chay ------------- 86 SE 3.4 |
Posted By: CFoss
Date Posted: 24 February 2010 at 11:45am
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BTW guys, I found a wonderful resource for REAL service manuals for all our cars: http://www.fieronews.net/fusion/downloads.php Check it out. I was downloading all last night. They have all the schematics and such and actually match what's on my car (Blown away)! Chay ------------- 86 SE 3.4 |
Posted By: Patrick
Date Posted: 24 February 2010 at 12:29pm
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Are there manuals there that aren't already on the club's server http://www.captfiero.com/paperbased/ - Here ? Dave, perhaps you'd like to comment on this.
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CFoss wrote:Posted By: Dr.Fiero
Date Posted: 24 February 2010 at 2:26pm
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Wow... mega load of stuff! Few videos there that I'd even forgotten about! Brings back some memories! I shot a bunch of them. The 'strip' video was taken from my balcony, looking down onto the driveway of my house. We had a bylaws nazi sitting in his car about 200ft up the street scoping us out... we thought about going up there with 10 of us, and flipping his car - but thought better of it. ;) |
Posted By: Capt Fiero
Date Posted: 25 February 2010 at 12:51am
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A ton of that video was ripped from our club server. Yes he asked first. We have over 15gig of Tech and assorted Videos on our dir. http://videos.westcoastfieros.com/ - http://videos.westcoastfieros.com/
Better have broadband. ------------- Capt Fiero 88 Fiero GT 5spd V6 Eight Fifty Seven GT V8 5spd. |
Posted By: Romeo
Date Posted: 25 February 2010 at 1:14pm
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B.H.B. Blowing a fuse every time would imply a short to ground before the bulbs, or a short to power after them. Not sure how much that'll help you though. Look for spot where wires could rub on metal, or rub into eachother. ------------- Never shift into reverse without a back-up plan. |
Posted By: Dr.Fiero
Date Posted: 25 February 2010 at 2:39pm
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And don't get fooled by the old 'shorted bulb'.Doesn't happen too often, but it can. |
Posted By: Patrick
Date Posted: 25 February 2010 at 2:50pm
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Been there, done that. Yeah, sometimes it's the simplest things that throw us for a loop.
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Posted By: Romeo
Date Posted: 25 February 2010 at 4:56pm
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Hey, it's like my teacher told me, you can only ever have two problems with an electrical circuit: Too much resistance, or not enough. lol ------------- Never shift into reverse without a back-up plan. |