Thanks Vintage, looks like I have some work ahead of me.

 

Make sure the bulkhead connectors are secure and then follow the voltage, or no voltage until you find some with a test light or meter.

 

Double-check the wiring at the starter.

Clean that wire really, really well. Are you sure that wire is not RED instead of BLACK?

The middle wire on the solenoid should be RED not BLACK for the 1972 model year A-Body. In fact, for the 1972 model year I believe there are, in fact, two RED wires attached to the center battery lug (pole). The last black wire from the battery terminal to the solenoid was the 1969 model year. Post 1969 that wire is RED.

PREAMBLE: I know nothing w/ regard to the engine wiring harness you purchased which includes any wire sizes &/or wire colors.

I have wanted to put together this array of (supposedly) official CSM wiring diagrams illustrating battery wiring & horn relay JUNCTION BLOCK wiring comparisons from 1967 through 1972 for a number of years. IMO, it requires a level of thought deeper than how we often communicate wiring scenarios on this site. There have been SIGNIFICANT departures in wiring and nomenclature by Oldsmobile over the years. We routinely communicate Oldsmobile "official" COLOR wiring diagrams are located in the Chassis Service Manual (CSM) for each applicable year. Therefore, let's examine how this plays out.

NOTE: Each wiring diagram is from the applicable CSM model year for the A-Body series. 1967 through 1969 employs a single BLACK wire from the battery to the starter solenoid (these people must surely have been smoking crack cocaine). Pay close attention to the "business end" of the Battery wires to the JUNCTION BLOCK and to the SOLENOID. There are significant departures from what began in 1967 through and to include 1972 (where there are, in fact, TWO RED WIRES located on the SOLENOID (unless someone wants to challenge this as misinformation - please do speak up). At one point Oldsmobile refers to the battery as the ENERGIZER [1969] (they must have been sleeping w/ the bunny). And, the 1969 model year they refer to the horn relay junction block as the Power Take Off (someone was raised on a farm). If there's any consistency it's the inconsistency displayed in these wiring diagrams. In each of the following images, I refer to the "business end" of the wiring diagram as that which encompasses the wiring between the battery, the junction & the solenoid/starter. You be the judge.

I've heard someone on this site state (in other threads/posts) wiring color doesn't matter. It does matter if you're following an "official" Oldsmobile CSM for each applicable model year & series of vehicle. No one (on this site) has yet to demonstrate the explicit disparities in wiring diagrams at the "business end"; so, I thought I'd present the challenge which "might" find its way into a "sticky" someday (heaven forbid).









1967 - Black Wire

1968 - Black Wire

1969 Black Wire (Power Take Off = JUNCTION BLOCK)


1970 - Two INDEPENDENT red wires from battery to JUNCTION BLOCK and solenoid/starter.

1971

1972 - One red wire from BATTERY to SOLENOID and then a separate red wire from SOLENOID to JUNCTION BLOCK.