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Mystery relays... by CSM842M4
Started on: 12-06-2018 10:41 AM
Replies: 16 (173 views)
Last post by: olejoedad on 12-07-2018 01:03 AM
CSM842M4
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Report this Post12-06-2018 10:41 AM Click Here to See the Profile for CSM842M4Click Here to Email CSM842M4Send a Private Message to CSM842M4Edit/Delete MessageReply w/QuoteDirect Link to This Post

Finally got to roll the '86 GT into the garage to start adressing its many issues. Among the first is a host of electrical stuff that doesn't work, and some un-professionally "repaired" wiring issues. One of those is a jumper wire from the black/red wire at the radiator fan to one of the wires on one of two relays hanging on the evaporator enclosure under the boot/trunklid/whatever. Have been trying to discern the function of these two relays without success. If they control the headlights and/or headlight motors, that would kind of make sense, since one side doesn't work at all, motor or light. Any/all input is greatly appreciated. Thanks in advance - Chris

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ltlfrari
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Report this Post12-06-2018 11:10 AM Click Here to See the Profile for ltlfrariClick Here to visit ltlfrari's HomePageClick Here to Email ltlfrariSend a Private Message to ltlfrariEdit/Delete MessageReply w/QuoteDirect Link to This Post

I believe one is AC power and the other is for the high speed blower

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Gall757
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Report this Post12-06-2018 11:45 AM Click Here to See the Profile for Gall757Send a Private Message to Gall757Edit/Delete MessageReply w/QuoteDirect Link to This Post

That graphic is a mess......'front of car'?.....looks like rear of car to me.

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olejoedad
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Report this Post12-06-2018 11:54 AM Click Here to See the Profile for olejoedadClick Here to Email olejoedadSend a Private Message to olejoedadEdit/Delete MessageReply w/QuoteDirect Link to This Post

The relays are in the front of the car, but the arrow in the graphic is pointing the wrong direction.

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CSM842M4
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Report this Post12-06-2018 12:18 PM Click Here to See the Profile for CSM842M4Click Here to Email CSM842M4Send a Private Message to CSM842M4Edit/Delete MessageReply w/QuoteDirect Link to This Post

Thanks, guys (and/or girl/s?). My instinct is that the A/C power relay controls power to the compressor/clutch, and the high-speed blower relay has the heavier wires (pink) to run the blower motor? Two 16 gauge brown wires into and out of the A/C power relay? Not sure which way the previous owner was trying to go, but either powering the fan off the power relay or the other way around. Joy. Oh, well. Knew it was going to be a while before it was ready to drive hard. The Tail of the Dragon will wait...

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CSM842M4
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Report this Post12-06-2018 01:20 PM Click Here to See the Profile for CSM842M4Click Here to Email CSM842M4Send a Private Message to CSM842M4Edit/Delete MessageReply w/QuoteDirect Link to This Post

By the way, any input on where I might find the radiator fan relay, fuel pump relay and rear brake/turn signal relays? Think I found them near the left hood hinge on the wife's '84 2M4, but not so much on MY car...

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ltlfrari
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Report this Post12-06-2018 01:32 PM Click Here to See the Profile for ltlfrariClick Here to visit ltlfrari's HomePageClick Here to Email ltlfrariSend a Private Message to ltlfrariEdit/Delete MessageReply w/QuoteDirect Link to This Post

The graphic is from the Factory Service Manual, don't blame me!

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theogre
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Report this Post12-06-2018 01:36 PM Click Here to See the Profile for theogreClick Here to visit theogre's HomePageSend a Private Message to theogreEdit/Delete MessageReply w/QuoteDirect Link to This Post

AC/Heat blower use 3 resistors and relay at high speed. Relay is off when Blower is at lower speeds or off.

Gen1 HL motors use 3 relays. One at each motor to open and One to close both.

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ltlfrari
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Report this Post12-06-2018 01:42 PM Click Here to See the Profile for ltlfrariClick Here to visit ltlfrari's HomePageClick Here to Email ltlfrariSend a Private Message to ltlfrariEdit/Delete MessageReply w/QuoteDirect Link to This Post

According to the book, the fuel pump and coolant fan relays supposed to be near the drivers side deck lid hinge (ie, at the rear of the car) and they've been in the same place on all 3 Fieros I've owned so I am guessing it's pretty stock location. If not there then someone moved them.
Don't think the brake lights have relays, just direct wired. Turn signal flasher is under dash near the steering column, no other relay though, just direct wired.

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CSM842M4
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Report this Post12-06-2018 02:34 PM Click Here to See the Profile for CSM842M4Click Here to Email CSM842M4Send a Private Message to CSM842M4Edit/Delete MessageReply w/QuoteDirect Link to This Post

More thanks! By accident, I discovered that Fiero Store has SOME relay locations listed in their Tech tips section. Shows cooling fan relay in front of the left headlight, but doesn't state years or models. Nice to know there's another resource available.

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CSM842M4
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Report this Post12-06-2018 02:58 PM Click Here to See the Profile for CSM842M4Click Here to Email CSM842M4Send a Private Message to CSM842M4Edit/Delete MessageReply w/QuoteDirect Link to This Post

Yeah, I think I just found the fuel pump and fan relays. Right where ltlfrari said. Had to remove the left side cover/vent to find it. Thinking back, I believe that's where the 4 relays are on the '84, too.

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olejoedad
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Report this Post12-06-2018 03:09 PM Click Here to See the Profile for olejoedadClick Here to Email olejoedadSend a Private Message to olejoedadEdit/Delete MessageReply w/QuoteDirect Link to This Post

As to the radiator fan relay, the 84 relay is unique, 85-87 used the same relay, 88 relay is unique.

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theogre
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Report this Post12-06-2018 05:14 PM Click Here to See the Profile for theogreClick Here to visit theogre's HomePageSend a Private Message to theogreEdit/Delete MessageReply w/QuoteDirect Link to This Post

 
quote
Originally posted by ltlfrari:
According to the book, the fuel pump and coolant fan relays supposed to be near the drivers side deck lid hinge (ie, at the rear of the car) and they've been in the same place on all 3 Fieros I've owned so I am guessing it's pretty stock location. If not there then someone moved them.
Don't think the brake lights have relays, just direct wired. Turn signal flasher is under dash near the steering column, no other relay though, just direct wired.
Don't know what "book" you have... that is wrong.
FP and AC clutch is in back, outboard to left deck hinge. If you think 1 is bad many just switch plugs because both use same relay and see if "fix" the problem.
Rad Fan is in Front of left HL assem, outboard to left hood hinge.

Only 84 have relays on rear lights. was so all rear bright red work for brake/turn.
Later notches stop that so only 2 lights each side work for brake/turn.

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theogre
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Report this Post12-06-2018 05:17 PM Click Here to See the Profile for theogreClick Here to visit theogre's HomePageSend a Private Message to theogreEdit/Delete MessageReply w/QuoteDirect Link to This Post

 
quote
Originally posted by olejoedad:
As to the radiator fan relay, the 84 relay is unique, 85-87 used the same relay, 88 relay is unique.
84 uses 2 relays... non-AC or AC because AC cars uses 2 speed rad fan.

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ltlfrari
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Report this Post12-06-2018 05:31 PM Click Here to See the Profile for ltlfrariClick Here to visit ltlfrari's HomePageClick Here to Email ltlfrariSend a Private Message to ltlfrariEdit/Delete MessageReply w/QuoteDirect Link to This Post

Ogre, 'book' is 87 Factory Service Manual. Just repeating what it has in there

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CSM842M4
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Report this Post12-06-2018 06:54 PM Click Here to See the Profile for CSM842M4Click Here to Email CSM842M4Send a Private Message to CSM842M4Edit/Delete MessageReply w/QuoteDirect Link to This Post

Okay, my '86 GT 2.8 4-speed has 2 relays in back, neither has the heavier wire for the fan. One relay in front, other than the three for headlights and two at evaporator, and it HAS the heavier wire. Maybe something was changed for '87 (or mid-year) for some reason. My Chiltons manual has a lot of good information in it, but it's lacking in some areas. The info on Fiero Store is handy, but I wish it were more detailed. And I wish I had my own factory service manual.

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olejoedad
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Report this Post12-07-2018 01:03 AM Click Here to See the Profile for olejoedadClick Here to Email olejoedadSend a Private Message to olejoedadEdit/Delete MessageReply w/QuoteDirect Link to This Post

FSM reprints are available and are well worth the price paid.

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