Re: electrical wiring [again]

Posted by HH56 On 2024/1/5 16:12:55

There is a bit of difference in the main harness between PB and non PB cars.. A couple of the differences are in regular Ultramatic cars there is a combination neutral safety switch/backup light switch mounted on the steering column inside the engine compt near the firewall so the starter wire from the ign sw to the solenoid and the backup light wires go to that location.

In a PB car the neutral safety interlock is done by a relay on the inner fender next to the shift relays. For the PB car the relay interrupts the wire from the ign sw to solenoid but is operated by a wire coming from the push buttons. Backup light power is provided directly from the push button assembly and the backup light wire is connected via an inline connector to another wire coming from the push buttons. Most of that wiring is in the main loom but exits in different spots.

As to working on the dash, at least in 56 the column is short and easy to remove. I have not done it but have read where people had removed all the upper dash screws that are under the windshield molding but left the two large bolts at the lower corners loosened but still installed. With the steering column removed they were able to pull the top out to rotate the dash slightly downward and support it in that position --- but there is a huge maybe it is not that easy involved.

In most cars the wire loom is positioned around and thru the steering column brace. In most cases without removing the brace the loom will not have enough slack to allow the dash to move much without putting a huge stress on the gauges and wiring. Removing the brace does involve getting under and depending on what else is in the way some bolts can be hard to access and if I remember two are 12 point that need a special socket. Even then the loom can still present a problem depending on how or if it is twisted thru the brace.

You also need to watch out for the Bowden cables that operate the wiper, heater, and vents and make sure they do not get pulled or kinked. I think the radio tuner section above the glovebox also has a strap that bolts to the firewall that would need to be disconnected.