Th400 and tach wiring locations - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**70STOVEBOLT** · 12-09-2021, 06:43 PM

Converting my 70 to a tach dash. I have a TH400 trans now and the kickdown wire is currently routed through a grommet in the firewall to the left of the bulkhead connector and to the right of the emergency brake cable grommet. Where was the tach wire routed through the firewall with a TH400 transmission? I have searched but could not find the info. Pics would be good too.

Six862m6 · 12-10-2021, 09:05 AM

Quote:

Originally Posted by 70STOVEBOLT

Converting my 70 to a tach dash. I have a TH400 trans now and the kickdown wire is currently routed through a grommet in the firewall to the left of the bulkhead connector and to the right of the emergency brake cable grommet. Where was the tach wire routed through the firewall with a TH400 transmission? I have searched but could not find the info. Pics would be good too.

I don't know if my old thread will help you or not but I was doing some similar research for my '68 just a bit back.... That being said, the wires and bulkheads on '67s & '68s are not the same as 69 and up. We're reasonably sure that my truck was originally a TH400 and had a tach though, so it may still be helpful. My original tach wire was running in the area that it sounds like your kickdown is. It's marked in the pictures. Turns out, the cut wire that I have marked in the pictures as "WTH??" was my TH400 kickdown wire. I marked it as that at the time because it was cut in the engine compartment and not connected to anything (still had the connector on it though) in the cab (I got the truck with a TH350 in it) and I had no idea what it was for.

https://67-72chevytrucks.com/vboard/...d.php?t=825672

**70STOVEBOLT** · 12-10-2021, 12:06 PM

Six, thanks for your post, I will check out the thread when I get time.

12-09-2021, 06:43 PM	#1
70STOVEBOLT Senior Member Join Date: Jun 2005 Location: Winona Lake, IN Posts: 6,212	Th400 and tach wiring locations Converting my 70 to a tach dash. I have a TH400 trans now and the kickdown wire is currently routed through a grommet in the firewall to the left of the bulkhead connector and to the right of the emergency brake cable grommet. Where was the tach wire routed through the firewall with a TH400 transmission? I have searched but could not find the info. Pics would be good too. __________________ 70 C/10 SWB 402/TH400/3.73 "The Needy Beast" 200,000 Mile Club Disc Brake Club Owner installed options: Front Sway Bar Power Steering Power Brakes Cigar Lighter Courtesy Lights Deluxe Side Markers Wiper Delay Power windows Power Locks Coming soon: EFI 2015 Silverado 1500 LS 4.3/6L80/3.23

12-10-2021, 12:06 PM	#3
70STOVEBOLT Senior Member Join Date: Jun 2005 Location: Winona Lake, IN Posts: 6,212	Re: Th400 and tach wiring locations Six, thanks for your post, I will check out the thread when I get time. __________________ 70 C/10 SWB 402/TH400/3.73 "The Needy Beast" 200,000 Mile Club Disc Brake Club Owner installed options: Front Sway Bar Power Steering Power Brakes Cigar Lighter Courtesy Lights Deluxe Side Markers Wiper Delay Power windows Power Locks Coming soon: EFI 2015 Silverado 1500 LS 4.3/6L80/3.23



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