'68 Dash Gauge(s) Wiring - Conversion from lamps? - Chevelle Tech
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post #1 of 14 (permalink) Old Dec 16th, 15, 7:42 AM Thread Starter
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Bruce
 
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'68 Dash Gauge(s) Wiring - Conversion from lamps?

I bought this '68 el Camino SS 396 back in July, it has the dash gauges in it, the Alt/Gen gauge did not work and the temp gauge registered some change when the engine warmed up but could tell it was not correct (might be the engine temp sensor?).

Make a long story short, I needed to replace the dash bezel since a previous owner cut the back of the radio mounting area out, got a real nice one, media blasted it, dyed and detailed it, so from that perspective ready to go. Pulled the entire dash out as well as the motor compartment wiring apart (do it on all the cars I get to make sure everything is wired correctly and no crappy splices, etc.....which I have found several already in this '68 and corrected!).

Now here is where I need some help....

The '68 el Camino apparently was originally non-gauge's from the factory, a previous owner added the gauges/tach (BTW, tach worked, just not wired very well, corrected that). In the gauge pod, the fuel is fine, the oil pressure is now manual, so those 2 gauges I don't have to worry about. The wiring for the Alt/Gen is not correct and I need some better reference for the temp gauge to make sure it is wired correctly. I have the '68 Chevelle/el Camino Assembly Manual and only wiring diagrams I can find (pages 12-D1 thru 12-D5) only make reference to dash wiring for the lamps (idiot lights), nothing for the gauges?

Need some help to find correct dash/motor compartment wiring diagrams for U14 RPO optional gauges?

'68 el Camino SS 396/325hp, 4 Speed, 3.31, Buckets, AC
'72 el Camino SS 454 4 Speed, 3.73 Eaton LSD, Buckets, AC
'75 el Camino SS, 400 SB, 200R4, 3.42 LSD, AC, Swivel Buckets, PW, PDL
'87 el Camino SS 305 TPI, 200R4, 3.73 LSD
'87 Buick Grand National (Hardtop, Bucket Seats)
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post #2 of 14 (permalink) Old Dec 16th, 15, 11:20 AM
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Re: '68 Dash Gauge(s) Wiring - Conversion from lamps?

You are correct, the diagram is not there for gauges. Make sure you have the correct temp sending unit for gauges, (thermistor) not idiot lights (temp switch). As far as the amp meter, the wiring under the hood uses a wire run from the alt to the battery to determine charging. This circuit is all the same for GM Cars with AMP meters in those days so look at other schematics. In my opinion this is the most difficult circuit to duplicate without the correct harness. I guess that's why manufacturers went to volt meters....
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post #3 of 14 (permalink) Old Dec 16th, 15, 11:48 AM Thread Starter
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Bruce
 
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Re: '68 Dash Gauge(s) Wiring - Conversion from lamps?

So the heavy wire that runs from the alternator to the battery is charging the battery, but I think that runs from the alternator to the voltage regulator (separate from alternator, mounted on radiator support), from there to the battery?

Question is should the wire going to the gauge be in parallel or series?

'68 el Camino SS 396/325hp, 4 Speed, 3.31, Buckets, AC
'72 el Camino SS 454 4 Speed, 3.73 Eaton LSD, Buckets, AC
'75 el Camino SS, 400 SB, 200R4, 3.42 LSD, AC, Swivel Buckets, PW, PDL
'87 el Camino SS 305 TPI, 200R4, 3.73 LSD
'87 Buick Grand National (Hardtop, Bucket Seats)
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post #4 of 14 (permalink) Old Dec 16th, 15, 3:05 PM
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Wink Re: '68 Dash Gauge(s) Wiring - Conversion from lamps?

www.classiccarwiring.com sells a very nice colored wiring diagram that has the gauge cluster wiring on it. Problem is that part of the diagram (battery gauge) isn't correct.
Look through this thread- www.chevelles.com/forums/showthread.php?t=529090

BillL

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post #5 of 14 (permalink) Old Dec 16th, 15, 3:32 PM Thread Starter
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Re: '68 Dash Gauge(s) Wiring - Conversion from lamps?

Quote:
Originally Posted by Ark68SS View Post
www.classiccarwiring.com sells a very nice colored wiring diagram that has the gauge cluster wiring on it. Problem is that part of the diagram (battery gauge) isn't correct.
Look through this thread- www.chevelles.com/forums/showthread.php?t=529090

BillL
Thanks Bill! GREAT info, just what I needed! :-)

'68 el Camino SS 396/325hp, 4 Speed, 3.31, Buckets, AC
'72 el Camino SS 454 4 Speed, 3.73 Eaton LSD, Buckets, AC
'75 el Camino SS, 400 SB, 200R4, 3.42 LSD, AC, Swivel Buckets, PW, PDL
'87 el Camino SS 305 TPI, 200R4, 3.73 LSD
'87 Buick Grand National (Hardtop, Bucket Seats)
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post #6 of 14 (permalink) Old Dec 16th, 15, 6:08 PM Thread Starter
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Bruce
 
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Re: '68 Dash Gauge(s) Wiring - Conversion from lamps?

OK, one last question about the temp gauge wiring.......

With the original temp gauge wiring with the idiot lights the wiring diagram in the Assembly Manual shows the dark green wire going back to the temp sensor in the block and the pink wire going to the oil pressure lamp socket. With the elimination of the oil pressure lamp, where should the pink wire on the temp gauge get connected to?

'68 el Camino SS 396/325hp, 4 Speed, 3.31, Buckets, AC
'72 el Camino SS 454 4 Speed, 3.73 Eaton LSD, Buckets, AC
'75 el Camino SS, 400 SB, 200R4, 3.42 LSD, AC, Swivel Buckets, PW, PDL
'87 el Camino SS 305 TPI, 200R4, 3.73 LSD
'87 Buick Grand National (Hardtop, Bucket Seats)
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post #7 of 14 (permalink) Old Dec 17th, 15, 12:05 PM
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Wink Re: '68 Dash Gauge(s) Wiring - Conversion from lamps?

The pink wire goes to the + terminal of the temp gauge.
The pink wires provide switched 12 volt power to the gauges or idiot lights. One pink wire is connected to the fuel gauge, one to the temp gauge, and the other will not be hooked up because the oil pressure gauge is mechanical.
Look closely at the pictures in the post I linked and be sure that you attach the wires to the proper terminals on the gauges or they will not work.
BillL

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Good livin' will speed it up, but it's worth it.
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post #8 of 14 (permalink) Old Dec 17th, 15, 12:14 PM Thread Starter
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Re: '68 Dash Gauge(s) Wiring - Conversion from lamps?

Quote:
Originally Posted by Ark68SS View Post
The pink wire goes to the + terminal of the temp gauge.
The pink wires provide switched 12 volt power to the gauges or idiot lights. One pink wire is connected to the fuel gauge, one to the temp gauge, and the other will not be hooked up because the oil pressure gauge is mechanical.
Look closely at the pictures in the post I linked and be sure that you attach the wires to the proper terminals on the gauges or they will not work.
BillL
AHHHH! The pink wire on the temp gauge is not currently hooked up. So the pink wire with 12V+ gives the gauges (temp & fuel) the voltage and the sensors (both fuel and temp) provide the impedance to set the gauge(s) to the correct reading?

So that is probably why my temp gauge was not working correctly, not sure where it would get voltage from since the pink wire is not hooked up to any power feed, but it did read just above the bottom line when the motor warmed up, but did not go any higher.

'68 el Camino SS 396/325hp, 4 Speed, 3.31, Buckets, AC
'72 el Camino SS 454 4 Speed, 3.73 Eaton LSD, Buckets, AC
'75 el Camino SS, 400 SB, 200R4, 3.42 LSD, AC, Swivel Buckets, PW, PDL
'87 el Camino SS 305 TPI, 200R4, 3.73 LSD
'87 Buick Grand National (Hardtop, Bucket Seats)
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post #9 of 14 (permalink) Old Dec 20th, 15, 6:35 AM Thread Starter
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Bruce
 
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Re: '68 Dash Gauge(s) Wiring - Conversion from lamps?

Quote:
Originally Posted by Ark68SS View Post
www.classiccarwiring.com sells a very nice colored wiring diagram that has the gauge cluster wiring on it. Problem is that part of the diagram (battery gauge) isn't correct.
Look through this thread- www.chevelles.com/forums/showthread.php?t=529090

BillL
Bill, ran the new wires yesterday to the connection block behind the battery and to the voltage regulator bringing them up into the dash (redid all the wire wraping too!).

Based on the pictures that I got out of the post above (I also used that as a great example to mark the back of my instrument cluster gauge back!), any idea which connector to the AMP gauge should be connected to voltage regulator and which one to the connection block behind the battery? As stated, getting these backwards will show a discharge on the gauge instead of it charging (which I did in my '72, still have not had a chance to pull the dash apart to correct it). Using the labels (BLK & BLK/WHT) they used in picture, which one goes to the voltage regulator and the connection block?
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'68 el Camino SS 396/325hp, 4 Speed, 3.31, Buckets, AC
'72 el Camino SS 454 4 Speed, 3.73 Eaton LSD, Buckets, AC
'75 el Camino SS, 400 SB, 200R4, 3.42 LSD, AC, Swivel Buckets, PW, PDL
'87 el Camino SS 305 TPI, 200R4, 3.73 LSD
'87 Buick Grand National (Hardtop, Bucket Seats)
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post #10 of 14 (permalink) Old Dec 20th, 15, 2:47 PM
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Re: '68 Dash Gauge(s) Wiring - Conversion from lamps?

check this webpage out it should help you with your install.i know this is for a 69 gauges but the wiring of the factory style gauges should be the same.

http://www.noneckschevelle.com/techtips1.htm

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post #11 of 14 (permalink) Old Dec 20th, 15, 4:50 PM Thread Starter
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Re: '68 Dash Gauge(s) Wiring - Conversion from lamps?

Quote:
Originally Posted by wambams69ss396 View Post
check this webpage out it should help you with your install.i know this is for a 69 gauges but the wiring of the factory style gauges should be the same.

http://www.noneckschevelle.com/techtips1.htm
Thanks for the reply.

Read thru the whole forum post (noneckschevelle) and looked at the pictures/diagrams. The one diagram for the AMP meter showed the connections that I have done. On the diagram, states "if your gauge reads backwards, then swap the wires on the back of the amp gauge".

That was the purpose of me asking which connection goes to the horn relay/voltage regulator and which one goes to the connection block behind the battery!

I don't want to have to pull the dash out again to swap the wires!

'68 el Camino SS 396/325hp, 4 Speed, 3.31, Buckets, AC
'72 el Camino SS 454 4 Speed, 3.73 Eaton LSD, Buckets, AC
'75 el Camino SS, 400 SB, 200R4, 3.42 LSD, AC, Swivel Buckets, PW, PDL
'87 el Camino SS 305 TPI, 200R4, 3.73 LSD
'87 Buick Grand National (Hardtop, Bucket Seats)
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post #12 of 14 (permalink) Old Dec 21st, 15, 3:13 PM
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Wink Re: '68 Dash Gauge(s) Wiring - Conversion from lamps?

Quote:
Originally Posted by wambams69ss396 View Post
i know this is for a 69 gauges but the wiring of the factory style gauges should be the same.

http://www.noneckschevelle.com/techtips1.htm
Some similarities, but not the same.

The black wire goes to the connector in front of the battery, the black/white to the relay. Although the factory didn't, I spliced a 4" long 20ga fusible link to the wires for peace of mind.
BillL

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post #13 of 14 (permalink) Old Dec 21st, 15, 4:32 PM Thread Starter
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Re: '68 Dash Gauge(s) Wiring - Conversion from lamps?

Quote:
Originally Posted by Ark68SS View Post
Some similarities, but not the same.

The black wire goes to the connector in front of the battery, the black/white to the relay. Although the factory didn't, I spliced a 4" long 20ga fusible link to the wires for peace of mind.
BillL

Mucho Gracias Bill! Now I know what wires to connect to what lugs on the back of the AMP Gauge!

'68 el Camino SS 396/325hp, 4 Speed, 3.31, Buckets, AC
'72 el Camino SS 454 4 Speed, 3.73 Eaton LSD, Buckets, AC
'75 el Camino SS, 400 SB, 200R4, 3.42 LSD, AC, Swivel Buckets, PW, PDL
'87 el Camino SS 305 TPI, 200R4, 3.73 LSD
'87 Buick Grand National (Hardtop, Bucket Seats)
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post #14 of 14 (permalink) Old Dec 21st, 15, 5:47 PM Thread Starter
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Re: '68 Dash Gauge(s) Wiring - Conversion from lamps?

Quote:
Originally Posted by Ark68SS View Post
spliced a 4" long 20ga fusible link to the wires for peace of mind.
BTW, meant to add that I spliced in AGC fuseholders for each wire, initially put in 2AMP fuses as suggested in the other thread.

'68 el Camino SS 396/325hp, 4 Speed, 3.31, Buckets, AC
'72 el Camino SS 454 4 Speed, 3.73 Eaton LSD, Buckets, AC
'75 el Camino SS, 400 SB, 200R4, 3.42 LSD, AC, Swivel Buckets, PW, PDL
'87 el Camino SS 305 TPI, 200R4, 3.73 LSD
'87 Buick Grand National (Hardtop, Bucket Seats)
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