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Old 02-06-2019, 01:21 AM   #1
BIG ORANGE
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91 non tach/ 94 tach

What has to be done to make this work? I got a 91 truck that's non tach and have a 94 parts truck that has a tach cluster.
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Old 02-07-2019, 09:52 PM   #2
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Re: 91 non tach/ 94 tach

The 91 is the half moon gauges right? I think those are quite different than 94 and requires a lot of work-connector on the back is different. They only made a “plug and play” for a 91 for like 6 months

I have a 92 which is needle style not half moon. A tach cluster was plug and play
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Old 02-08-2019, 06:13 AM   #3
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Re: 91 non tach/ 94 tach

It can be done, but needs to be repinned. 91 with tach will almost be plug n play. I have a 91 tach dash if ur interested.
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Old 02-08-2019, 10:06 PM   #4
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Re: 91 non tach/ 94 tach

Well here's where I'm at with it now. I've removed the 94 dash as a complete dash, unplugged the harness from the firewall bulkhead. Do I need to just remove the engine harness under the hood from the 94 and put it in the 91 with the complete dash swap out?
Thanxs guys ..
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Old 02-09-2019, 10:03 PM   #5
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Re: 91 non tach/ 94 tach

Or will plugging the 94 bulkhead into the 91 harnesses at the firewall work??
Really need answer's guy..
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Old 02-11-2019, 09:13 PM   #6
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Re: 91 non tach/ 94 tach

Come on guys, I can't find a answer to this any where on Google.
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Old 02-12-2019, 04:53 PM   #7
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Re: 91 non tach/ 94 tach

There is no engine or transmission information so I can't answer some questions you sent me in the private message.

1994 pickups with automatic transmissions were electronically shifted by the computer. The only 1991 trucks that were electronically shifted were the big blocks that had the 4L80E transmission. A 1994 with an automatic transmission has an 8192 baud rate PCM. A 1991 pickup without a big block using a 4L80E would have a 160 Baud rate C3 ECM. There are very big differences in the wiring between these two vehicles.

Can a 1994 instrument panel be put in a 1991? - Yes but it will take a bit of work.

In 1991 the DRAC module was built into the instrument cluster. In 1994 the DRAC module was separate from the instrument panel assembly.

To put a 1994 instrument panel in a 1991 you are going to have to wire in a DRAC module to make it work. You will need the instrument panel connector from a 1994. You will have to recalibrate the DRAC module for your truck.
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Old 02-12-2019, 09:38 PM   #8
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Re: 91 non tach/ 94 tach

This all started out from the 91 having a destroyed dash, I was just hoping I could remove the dash out of 94 keeping it complete and bolt it into the 91. If I gotta, I will just remove all the wiring out of the 94 dash and just use the plastics of the dash. The tach cluster had nothing to do with trying to do the swap. Was just trying to simplify it but sounds like its anything but simple......lol
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Old 02-13-2019, 06:59 AM   #9
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Re: 91 non tach/ 94 tach

I found a 92 4x4 V6 5speed would this be of help? Wiring, tach cluster?
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Old 02-13-2019, 11:22 AM   #10
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Re: 91 non tach/ 94 tach

A 1992 would have the separate DRAC, wiring and plug for the DRAC, and correct instrument panel connector for a 1994 panel.

BUT, a instrument panel with a tachometer for a V6 is different then a V8.
It can be converted by change Capacitor C103.
Capacitor C103 with a V6 has a value of .0033uf (3300 pf)
Capacitor C103 with a V8 has a value of .002475uf (2475pf)
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Old 02-14-2019, 12:27 AM   #11
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Re: 91 non tach/ 94 tach

Quote:
Originally Posted by ChevyTech View Post
A 1992 would have the separate DRAC, wiring and plug for the DRAC, and correct instrument panel connector for a 1994 panel.

BUT, a instrument panel with a tachometer for a V6 is different then a V8.
It can be converted by change Capacitor C103.
Capacitor C103 with a V6 has a value of .0033uf (3300 pf)
Capacitor C103 with a V8 has a value of .002475uf (2475pf)
That sound good but my truck is a 91
I'm bout ready to replace the broken up plastic with the good 94 dash and wire it up with the 91 stuff and not look back..
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Old 02-14-2019, 07:42 AM   #12
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Re: 91 non tach/ 94 tach

With these trucks your best bet for swapping between design changes is find same year with what you want and do total swap wiring, electronics, components. Then it's just work. But that can be a needle in a haystack. Your decision is probably best
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Old 02-14-2019, 10:10 PM   #13
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Re: 91 non tach/ 94 tach

Quote:
Originally Posted by special-K View Post
With these trucks your best bet for swapping between design changes is find same year with what you want and do total swap wiring, electronics, components. Then it's just work. But that can be a needle in a haystack. Your decision is probably best
Yes and stick with old stuff, its alot easier to work on and to understand..
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