efather

I have been routing hoses and wires in the engine bay in the 72.

The AIM on UPC12 shows RPO A31 and RPO M40/backup lamp goes through the 4 hole grommet. Mine is an auto and does have power windows.

I am having trouble finding the wires that will go through it for those. Are these on the engine harness or the interior harness? any pics that show these? I did see an earlier post from Alan but that did not show all the wires and I didnt see the pink/green wires.

any help is appreciate.

Thanks in advance.

efather

Wow not sure I have ever seen such an empty post. To be honest I really cant tell in the AIM what could go through those last 2 holes. maybe is the case that they are not needed or will pan out once I started connecting the inside wiring.

Jud Chapin

Can u supply a pic of the grommet as it sits in the firewall. Are the holes large enuf for vacuum hoses. Some of the holes could be for options that your car doesn't have or had at one time and no longer has. Re a/c, on some Vettes there is a vacuum hose that goes from the a/c switch to the water control valve in one of the heater hoses.

Easy Mike

If memory serves, neither. The TH400 and the PW have their own harnesses. Check the AIM sections for each option. I believe each come out of the interior and through the grommet/firewall.

Alan 71

Hi E,
I didn't reply because I don't have either p/w or auto; so I wasn't sure.
Here's the grommet on my 71.
2 of the holes had a rubber membrane in them that would have been poked out if the hole was needed.
In this case, (71, sb, 4-speed), oil line, vacuum hose, back-up light connection.
Regards,
Alan

efather

Mike
Thats what confused me. the wire for the TH400 was part of the engine harness, the PW made no sense why they would some out into the engine bay at all.

Alan
The Backup light is the one I am having a hard time finding. there is 1 pair of wires with a plug in adapter that may be the wires I am looking for. What is the color of those backup wires?

I could have swore I saw it in the AIM 1 time, but have not been able to find it again. the section that I do find for that grommit just referes to the RPO number nothing more. The aim is tough sometimes with how they put the different models in there and some of the subtle differences between them.

Alan 71

Hi e,
The 4 hole grommet is shown on UPC 12, Sheet C2.
I mislead you it's not a vacuum hose... it's the tach cable.
So the possibilities are oil pressure pipe, (they really do call it a pipe), RPO A31, Back-up lamps, RPO M40.
On my 71 the back up tail coming through the grommet is pink and light green wires, wrapped and with a connector.
You can JUST see it in this picture.
Regards,
Alan

tracdogg2

The back-up harness does not go thru the firewall on an automatic.
The power window harness does go thru the firewall to the circuit breaker mounted on the side of brake booster box.
Mike

Easy Mike

UPC A31 Sheet A1 Power window harness comes out of the interior through the grommet.

UPC M40 Sheet A9 Kick down switch wiring comes in through the grommet.

efather

Thanks to both mikes for pointing out the UPC and the fact of the circuit breaker (i forgot about it).

much appreciated