[MCronkGTO]

My car came with a dealer installed hood tach (68 GTO RA convertible). It is on the original sales invoice. Is there a wiring diagram for a dealer installed hood tach? It appears the power is being connected to the power wire for the wiper motor with a non OEM splice connector. I am not sure how it should be connected.

Thanks!

Mark

[OG68]

This is from the 68 Service Manual

[Mcronk]

Thanks! I studied that in the manual but the resolution is not very good. Noticed that the wire that connects to negative side of coil has a fuse. Manual says it is a 1 amp fuse (on Firebird installation diagram).

The wires/connector that plugs into the tach harness had the other ends cut off. I am going to order a reproduction harness so I have the correct connectors.

I have another question for you. It appears the cowl on the 11A built car was never punched/drilled for the rear hood bumpers. I have them on my 05C built car. Was that a change during production? I had the same concern about the horn relay. The holes in the cowl were not punched/drilled and it was mounted near the firewall on the inner fender. Also the core support does not have the holes for the clips that retain the wiring and vacuum hoses that run across the front of the core support. I hate to drill holes in original parts that were not there originally. Have you heard or seen of this? Thanks for your help.

Mark

[OG68]

I think your cowl is an anomaly.
My Fremont 05A has a Chevelle model number on the cowl which makes sense since it was a General Motors Assembly (BOPC) plant as was Baltimore.
Chevy A bodies had the VR and Horn relay mounted on the core support. Possibly your cowl was intended for a Chevelle? Don't know.

There was a change in horn relays late in production. (June 1) A Craftsman Newsletter dated October 68 provides details. However, my 05A has the 2nd type of relay.

[OG68]

I went through my collection of 68 Craftsman Newsletters and Dealer Bulletins and didn't notice any mention of cowl changes with the exception of the horn relay. My 68 has only one wire hanger on the firewall. I believe this was for all 68 Tempest A bodies. The 69 model added two more.

[OG68]

Drawings from the 69 Assembly manual

[OG68]

Hood Bumpers

[Mcronk]

I think I figured out the horn relay location. I found an old picture from previous owner and I can see two holes that probably matched the first style relay (early build car). I suspect when he replaced the relay with the second style it would not match the holes of the first style and mounting tab is on top of first style relay and on bottom of second style so he mounted the second style on the inner fender near firewall. Now I need to decide if I want to reverse and go back to the first style? I did find a NORS first style relay on ebay. Pictures below for reference. BTW my 05C built car also has second style relay. However I know it is has been replaced.

I also have a copy of the 69 assembly manual but as you point out there are a lot of differences between 69 and 68. Both my 68 cars just have the one wire harness strap mounted on the firewall. I noticed on the hood bumper diagram that the middle bumper says "existing hole" and the bumper closer to the driver side says to drill hole at dimple. I do have a very small hole in the middle bumper location but not the correct sized for the proper screw. I do not even have a dimple for the location on driver side. Possibly a mistake/anomally.

Thanks again for your expertise.