1975 Chevy Vega Fuse Box (extra wires in front)

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1975 Chevy Vega Fuse Box (extra wires in front)

Postby robert123 » Wed Mar 30, 2016 6:15 am

1975 Chevy Vega Hatchback Fuse Box Wiring Question (sbc, 600cfm carb, auto trans, no a/c)
*Added: seems to be a stock sbc, mechanical fuel pump

1. The car ran good.
2. Then I messed with it. I decided to “improve” the weird wiring at the front of the fuse box….
3. Now the sbc (with HEI) runs a little rough -- about 90% good. Maybe its not getting enough current in the ignition circuit? It also backfires a bit out of the exhaust header.
4. In the photo, I tried to remake the wiring as the prior owner had it. Originally, it had a pink wire… hooked into a factory looking White plastic dual connector … hooked up to IGN port. (The white “dual connector” was about ½ the size of the black connector holding the Directional Flasher (?) in the photo. It had the original pink 16g wire going into the IGN port. On the side of the white connector there was an approx. 3" long, fat 10-12g wire, with ½" exposed wire on the end [somewhat corroded green] that went behind the partly dislodged DIR SIG & BACKUP fuse.)
5. If you check the factory wiring diagram for 75 Vega... it shows that the bottom of the DIR SIG & BACKUP fuse is NOT HOT (I don't know why. It is the only fuse with no connection on the bottom.)
6. The factory column ignition switch used to start and shut off the engine fine. Today (Wed) made the red exposed wire (behind dislodged fuse) contact the bottom of the fuse better -- and it runs great. So it starts normally with key ... and runs great ... but key doesn’t shut the engine off.
If I pull the pink and red wire the engine will keep on running. (To shut off engine, have to pull Neg battery terminal and #2 Sensing wire (bottom wire on Delco 3-Wire Alternator.)

(Added 5 days later; [1} on photo is not a Directional or Turn signal flasher; its a mystery cylinder with 3 terminals.......)


Main Questions
1. BEFORE I MESSED WITH THE WIRES… WAS THAT HOW THE FACORY WIRED IT (White dual connector, with a fat 10-12g wire running to the dislodged DIR SIG fuse)???
2. WHY WOULD THE PRIOR OWNER WIRE IT THAT WAY?
3. HOW CAN I FIX IT SO IT IS RELIABLE & WORKS GOOD ???
4. Thanks for your help.
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1975 Chevy Vega Fuse Box
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1973 Chevy Vega GT Hatchback, stock, 4-speed
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Re: 1975 Chevy Vega Fuse Box Wiring Question

Postby spencerforhire » Wed Mar 30, 2016 10:08 am

Looks like the prior owner tried to run a good ignition switched supply feed out to under the hood for the HEI. Whatever it's plugged into must not be supplying enough voltage to run properly. Not sure why the signal light feed is also tapped in. I suspect that if you trace that pink wire out to the HEI, the car would run better if you hooked it directly to the large pink wire from the ignition switch.
The "fleet"-
77 Vega Estate wagon- project(someday)will have TPI305/T-5, S-10 spindles/axles
72 Vega HB Drag Car -383/'Glide/9"(9.35@146.19)(5.94@117.28 1/8th)
76 Vega GT- 400/4spd/9" retired from active duty(rusty)
03 Silverado 2WD ex.cab (work truck/parts hauler)
04 Silverado 2WD ex.cab (retired)
06 Haulin' 20ft enclosed car transporter
93 Suburban- 350/4L60(retired)
00 Saturn SW2- wife's car
01 Saturn SC2- younger son's project
00 Saturn SL2- daughter's car
98 Saturn SW2- spare
and 3 more Saturn "parts cars"
Note- the very act of listing all of these has made me realize I have some kind of problem.....

Visit http://www.spencerforhire.ca
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Re: 1975 Chevy Vega Fuse Box Wiring Question

Postby zeke » Thu Mar 31, 2016 5:58 am

Eliminate the short pink chunk plugged into the IGN terminal outlet and see what happens. Could be causing your backfeed issue.

I'm thinking the flasher wire broke off the back of the fuse block so they stuffed it in the front maybe. Dunno why it's also hooked to IGN, maybe to try to correct for some other issue.

The factory definitely didn't wire it that way.
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Re: 1975 Chevy Vega Fuse Box Wiring Question

Postby spencerforhire » Thu Mar 31, 2016 6:28 am

Also, I forgot to mention the marrettes used to splice the wires on the dimmer switch are a FIRE HAZARD. Do yourself a favor and get those wires properly spliced; marrettes are not meant for automotive use, and will loosen up over time from vibration and corrosion.
The "fleet"-
77 Vega Estate wagon- project(someday)will have TPI305/T-5, S-10 spindles/axles
72 Vega HB Drag Car -383/'Glide/9"(9.35@146.19)(5.94@117.28 1/8th)
76 Vega GT- 400/4spd/9" retired from active duty(rusty)
03 Silverado 2WD ex.cab (work truck/parts hauler)
04 Silverado 2WD ex.cab (retired)
06 Haulin' 20ft enclosed car transporter
93 Suburban- 350/4L60(retired)
00 Saturn SW2- wife's car
01 Saturn SC2- younger son's project
00 Saturn SL2- daughter's car
98 Saturn SW2- spare
and 3 more Saturn "parts cars"
Note- the very act of listing all of these has made me realize I have some kind of problem.....

Visit http://www.spencerforhire.ca
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Re: 1975 Chevy Vega Fuse Box Wiring Question

Postby robert123 » Thu Mar 31, 2016 8:47 pm

spencerforhire wrote:Looks like the prior owner tried to run a good ignition switched supply feed out to under the hood for the HEI. Whatever it's plugged into must not be supplying enough voltage to run properly. Not sure why the signal light feed is also tapped in. I suspect that if you trace that pink wire out to the HEI, the car would run better if you hooked it directly to the large pink wire from the ignition switch.


Okay, thanks guys for the advice :th:
I'll work on those ideas tonight after work.
Sorting this out may take about a week. But I'm committed to getting this Vega on the road and running good-reliable -- to benefit mankind.
Will post updates every 1-2 days of progress.

Okay, here are the results of starting the car up and see how it would run with different wires pulled or attached.
1. (-) the two wires [red and pink]
+ starts (with key) + water temp gauge works (has been inop lately...)
- seems to run weak ... - key wont shut off engine ... - small internal knocking noise inside engine
2. (+) Pink IGN wire only
+ starts + temp gauge
- seems to run similar to above (same/weak) ... - key wont shut off engine
3. (+) Red wire (wire wrapped around dislodged fuse)
+ starts ... + temp gauge
+Runs better (More responsive) ... - key wont shut off

Also checked the Turn Signals with same wires pulled or attached:
1. Red and Pink connected
+ Turn signals work with key on or off
2. Red (stranded) wire only
+ Turn signals only work with key on
3. Pink wire only (connected to IGN)
+ Turn signals only work with key on
1973 Chevy Vega GT Hatchback, stock, 4-speed
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Re: 1975 Chevy Vega Fuse Box Wiring Question

Postby zeke » Sat Apr 02, 2016 7:57 am

"1. Red and Pink connected
+ Turn signals work with key on or off"

There's your backfeed issue, lose one of them and carry on troubleshooting.

Check voltage at ignition switch and out at HEI with key on.
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Re: 1975 Chevy Vega Fuse Box Wiring Question

Postby robert123 » Sat Apr 02, 2016 11:31 pm

UPDATE (3-4 days later):
I forgot to check Turn Signal operation with BOTH WIRES (RED & PINK) DISCONNECTED at fuse box:

4. Both Wires Disconnected
+ Turn Signals still work with key on.
(This is weird, because we thought the silver cylinder shaped "thing" was a flasher.)

So, my labeling in the original photo is wrong. The 2" long, silver cylinder shaped (3- terminal) "thing" is not a flasher. [We may be looking at some Al-Qaeda-Isis sabotage. Don't tell the wife or kiddies. We men will take care of business.] Anyway, the 4-way flasher is on the lower left part of fuse box. The Turn Signal flasher looks the same. I confirmed each was working just by holding it and sensing vibrations with the Turn Signal / 4-way flasher on.

NEW PHOTOS :mrgreen:

"We shall defend our 'island', whatever the cost may be, we shall fight on the beaches, we shall fight on the landing grounds, we shall fight in the fields and in the streets, we shall fight in the hills; we shall never surrender." Winston Churchill
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Re: 1975 Chevy Vega Fuse Box Wiring Question

Postby zeke » Sun Apr 03, 2016 1:01 am

Does your fuel gauge work?
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Re: 1975 Chevy Vega Fuse Box Wiring Question (*WASWAS)

Postby Monza Harry » Sun Apr 03, 2016 8:19 pm

Your electric choke wire should be plugged into the "IGN" terminal not the "ACC" terminal. Would only be problem [maybe] while listening to the radio on a coolish eve [spring/fall] with a 50* night after 1/2 an hour I would guess. Harry
I'm not a hoarder I'm a preservationist 78 Monza Spyder (Soon To Be 2+2 with Spoilers)
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Re: 1975 Chevy Vega Fuse Box Wiring Question

Postby robert123 » Sun Apr 03, 2016 9:12 pm

zeke wrote:Does your fuel gauge work?


Nooooooo.

Here's some more intel for you guys:
[tomorrow, I'm leaning toward trying Spencerforhire's idea of connecting-tapping into the Pink Ignition wire (from white plug) coming off steering column] -- then goes to the HEI.


V O L T A G E ....... R E A D I N G S

Car battery alone ........12.66 volts...........hooked up to car........12.44 volts

Zeke's advice -- "Check Voltage readings at Ignition Switch and out at HEI with Key On"
Ignition Switch at steering column (pink wire)......12.43 key on .............12.43 key off
HEI (1 wire at distributor) ............................. 12.43 key on ............ 12.43 key off


WIRE STATUS ...................... IGNITION SWITCH (Pink wire at st. column) ............ HEI
1. - 2 WIRES = .......................... 12.43.....................................................12.43
2. + Red Frayed Wire only ........... 12.44 .....................................................12.44
3. + Pink Wire to ACC only ........... 12.44 ....................................................12.44
4. + 2 Wires .............................12.44 ....................................................12.44
So, all are about 12.44 volts; or this part of ignition system is at about 12.44 volts.

5. IGN terminal at fuse box .......12.40 key on............. 12.43 key off

6. TURN SIGNAL - BACKUP LIGHTS FUSE (DISLODGED) ......................... .05 (top of fuse; key off) ............. .04 (bottom of fuse; key off)
...TURN SIGNAL - BACKUP LIGHTS FUSE (DISLODGED) ...................... 12.46 (top; key on) .................... 12.46 (bottom of fuse; key on)

7. TURN SIGNAL - BACKUP LIGHTS FUSE (seated normally) ................... .05 (top of fuse; key off) .............. .06 (bottom of fuse; key off)
...TURN SIGNAL - BACKUP LIGHTS FUSE 0(seated normally) ............... 12.46 (top of fuse; key on) ............ 12.46 (bottom of fuse; key on)

8. TURN SIGNAL - BACKUP LIGHTS (no fuse ) ................................... .02 (top of fuse; key off) ............... .03 (bottom of fuse; key off)
...TURN SIGNAL - BACKUP LIGHTS (no fuse) ................................. 12.41 (top of fuse; key on) ................ .03 (bottom of fuse; key on)

9. Alternator ...................................................................... 12.46 key on ...............................12.46 key off

10. Black 3-way Connector (Mysterious Cylinder [resistor?] plugs into this connector) ....... All 3 terminals .00 key on ........ .00 key off ....... (no power)

The main question is why did the prior owner wire it this way... and how to fix the wiring so it is more secure? Thanks
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Re: 1975 Chevy Vega Fuse Box Wiring Question (*WASWAS)

Postby zeke » Sun Apr 03, 2016 9:28 pm

Pull that mystery device (fluorescent lamp starter it looks like) out of that 3 pin plug and attach the plug to your fuel gauge. ;-)
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Re: 1975 Chevy Vega Fuse Box Wiring Question (*WASWAS)

Postby robert123 » Mon Apr 04, 2016 4:04 am

zeke wrote:Pull that mystery device (fluorescent lamp starter it looks like) out of that 3 pin plug and attach the plug to your fuel gauge. ;-)


Good idea.

Almost worked (maybe would work on GT). This is a 75 Hatch with a regular dash (and perhaps 20 prior owners....).
I checked the fuel gauge -- it appears to be the used stock one. The gauge has a brown 3 way connector with all horizontal terminals.
And pink, tan and black wires going to it.

Good try... fixed a couple of burnt out bulbs etc. while I was in there.
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Re: 1975 Chevy Vega Fuse Box Wiring Question

Postby spencerforhire » Mon Apr 04, 2016 6:51 am

By your voltage readings, it's obvious someone has the pink ignition feed hooked to Bat+ instead of Ign+. That is causing the drop when you hook up the battery. Try disconnecting all that mess at the fusebox and run your own new wire to the HEI.
The "fleet"-
77 Vega Estate wagon- project(someday)will have TPI305/T-5, S-10 spindles/axles
72 Vega HB Drag Car -383/'Glide/9"(9.35@146.19)(5.94@117.28 1/8th)
76 Vega GT- 400/4spd/9" retired from active duty(rusty)
03 Silverado 2WD ex.cab (work truck/parts hauler)
04 Silverado 2WD ex.cab (retired)
06 Haulin' 20ft enclosed car transporter
93 Suburban- 350/4L60(retired)
00 Saturn SW2- wife's car
01 Saturn SC2- younger son's project
00 Saturn SL2- daughter's car
98 Saturn SW2- spare
and 3 more Saturn "parts cars"
Note- the very act of listing all of these has made me realize I have some kind of problem.....

Visit http://www.spencerforhire.ca
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Re: 1975 Chevy Vega Fuse Box Wiring Question (*WASWAS)

Postby zeke » Mon Apr 04, 2016 8:56 am

robert123 wrote:Good idea.

Good try... fixed a couple of burnt out bulbs etc. while I was in there.


Just a guess based on the schematic showing the same colour wires and same number conductors and no gauge function.

Yeah, like Spence said, your hei appears to be 24/7, rewire that next for sure. Keep at it, you'll get it all sorted eventually.
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Re: 1975 Chevy Vega Fuse Box Wiring Question

Postby robert123 » Tue Apr 05, 2016 6:59 pm

spencerforhire wrote:By your voltage readings, it's obvious someone has the pink ignition feed hooked to Bat+ instead of Ign+. That is causing the drop when you hook up the battery. Try disconnecting all that mess at the fusebox and run your own new wire to the HEI.


Okay, I'll work on spencerforhire's advice, "Try disconnecting all that mess at the fusebox and run your won new wire to the HEI."

Here's some more photos. :mrgreen:

Photo 1 shows Mysterious Cylinder (3 terminal); looks Stock; Unopened; lightweight, feels like it is full of paper; no markings in Arabic.

Photo 2 shows: Max file size is 256...if you add text the File size Jumps way up/goes Anal. So had to make the photo small ....

a) about 1- foot of Excess tan wire folded over
b) Black Plug (the one with the Mysterious Cylinder) has 4 wires going into it [2 into 1 slot...]the 4th slot is empty; and the black wire goes up
about 4" and is spliced into another Black wire. Someone did a really Good job on the splice; and notice the black wires are wrapped
around each other for added strength.

c) Attractive splice
d) Bonus connector (connected to nothing)

Photo 3 shows [U.S. made screwdriver; strong, high quality; durable]:
pointing to attractive splice. Metal crimped splice joins 2 black wires above it to 3 black black wires below; then the black wires go to 3 separate connectors.

:mrgreen:
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