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| | | 1977 G20 Instrument cluster guages not working | Joined: May 2020 Posts: 75 journeyman | OP journeyman Joined: May 2020 Posts: 75 |
1977 Chevy G20 Ramjet 350 4L80E 4x4
| | | Re: 1977 G20 Instrument cluster guages not working | Joined: Jan 2014 Posts: 2,290 Likes: 137 veteran | veteran Joined: Jan 2014 Posts: 2,290 Likes: 137 | Looks like the correct gauge set to me, so the "computer" which is actually just the printed circuit board should be correct as well. I would be willing to bet money the previous owner has cut a bunch of wires they shouldn't have. Get a repair manual, a decent multimeter, and start tracing wiring.
The speedometer works off of a cable that has a coupling which will thread onto or push onto the back of the speedometer. It's hanging out of the dash in the 3rd picture.
Welcome to the site by the way. Go do an intro and let us know more about the van. | | | Re: 1977 G20 Instrument cluster guages not working | Joined: Dec 2017 Posts: 494 Likes: 21 addict | addict Joined: Dec 2017 Posts: 494 Likes: 21 | Before you go doing a bunch of tedious grunt work tracing wires, are you sure the plug wasn't just inserted upside-down? | | | Re: 1977 G20 Instrument cluster guages not working | Joined: May 2020 Posts: 75 journeyman | OP journeyman Joined: May 2020 Posts: 75 | Before you go doing a bunch of tedious grunt work tracing wires, are you sure the plug wasn't just inserted upside-down? Nice thought. I will check that tonight! Also on the side with the fuel and temp sensors there is a threaded piece on the back of the cluster. Is something supposed to attach to that? I will get pictures up soon with an intro.
1977 Chevy G20 Ramjet 350 4L80E 4x4
| | | Re: 1977 G20 Instrument cluster guages not working | Joined: May 2020 Posts: 75 journeyman | OP journeyman Joined: May 2020 Posts: 75 | Just tried flipping the plug and if I am not mistaken it can't be done. It looks like the plug has wider black plastic tabs on one side preventing it from installing the wrong way. I will look into tracing wires. I see some wiring diagrams for $20 online, are those any good?
1977 Chevy G20 Ramjet 350 4L80E 4x4
| | | Re: 1977 G20 Instrument cluster guages not working | Joined: Dec 2017 Posts: 494 Likes: 21 addict | addict Joined: Dec 2017 Posts: 494 Likes: 21 | Gotcha. The plug on my '78 can be pushed in either way. | | | Re: 1977 G20 Instrument cluster guages not working | Joined: May 2020 Posts: 75 journeyman | OP journeyman Joined: May 2020 Posts: 75 | Looks like the correct gauge set to me, so the "computer" which is actually just the printed circuit board should be correct as well. I would be willing to bet money the previous owner has cut a bunch of wires they shouldn't have. Get a repair manual, a decent multimeter, and start tracing wiring.
The speedometer works off of a cable that has a coupling which will thread onto or push onto the back of the speedometer. It's hanging out of the dash in the 3rd picture.
Welcome to the site by the way. Go do an intro and let us know more about the van. The speedometer cable was plugged in. Should that have been working even if the other gauges are not since it is its own cable?
1977 Chevy G20 Ramjet 350 4L80E 4x4
| | | Re: 1977 G20 Instrument cluster guages not working | Joined: May 2020 Posts: 75 journeyman | OP journeyman Joined: May 2020 Posts: 75 | Looks like the correct gauge set to me, so the "computer" which is actually just the printed circuit board should be correct as well. I would be willing to bet money the previous owner has cut a bunch of wires they shouldn't have. Get a repair manual, a decent multimeter, and start tracing wiring.
The speedometer works off of a cable that has a coupling which will thread onto or push onto the back of the speedometer. It's hanging out of the dash in the 3rd picture.
Welcome to the site by the way. Go do an intro and let us know more about the van. Is the Haynes repair manual the best option or should I try to hunt down a GM service manual?
1977 Chevy G20 Ramjet 350 4L80E 4x4
| | | Re: 1977 G20 Instrument cluster guages not working | Joined: Jan 2001 Posts: 2,964 Likes: 63 veteran | veteran Joined: Jan 2001 Posts: 2,964 Likes: 63 | The speedo cable should work on its own if attached properly. Pretty simple set-up, the cable goes from the back of the dash panel and attaches near the transmission. Would the threaded opening on the back be for an oil pressure line attachment. Haynes and Chilton manuals are usually the basics for repair, you can't beat having a factory manual, tons of detailed and comprehensive information along with illustrations, exploded views and wiring schematics. | | |
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