72 Cutlass .. Does anyone have a decent pic of the starter/solenoid wiring and how it is routed back to battery and or relay. I had starter runaway probably caused by battery wire on starter migrating over to the starter solenoid ?? Not good since it started engine while I was getting fuel. Previous owner thought this may have occurred before. Clearly the routing is incorrect. Probably fried the starter. The car has the tube to route the battery cable but it still seems like that brings it too close to the exhaust. Recommendations for a good battery to starter cable that has very little metal at the ring terminal at the starter. ?Thanks.

 

I realize you'd likely prefer a picture, but here is the wiring routing for your vehicle from the 1972 PIM.

 

assumed you ruled out your ignition switch ? The positive cable goes directly from the battery to the starter, no relay between the two. The solenoid (acts as your relay) is wired from the ignition switch via the neutral safety switch.

 

I assure you the routing of the cables did not cause your issue. It was caused by the contact of the S terminal wiring to main battery cable shorting or something within the starter solenoid.

 

Here are two well rated suppliers for new battery cables:

https://www.batterycablesusa.com/?gc...SAAEgL9u_D_BwE

https://www.custombatterycables.com/

Your battery cables shouldn't be frayed, damaged or green.

 

Correct , but I think it may have been the battery cable that hit the s terminal , possibly caused by the funky way the main bat cable was wired by previous owner. I think the end that attached to starter has too long of a metal spade, it may have worked over to touch the s terminal. I’m investigating later in day.

 

If the length of the ring terminal on the end of the battery cable is too long for your peace of mind, walk in to your local Lowe's or Home Depot and in the electrical section buy a piece of heat shrink tubing of the correct size, preferably the "glue" type and shrink it in place over the excess length. The heat shrink is generally good for 600 volts so will work fine in a 12 volt system. Use the wife's hair dryer to shrink it, not an open flame like the "roadkill" guys.

 

Thanks for the idea Jim. I shrunk wrapped all four wires. Looks like I may have saved the starter. 10 cycles so far so good. Not sure how bad it got during the runaway till I was able to disconnect battery. ( it was starting to smoke). Any thoughts on how long the starter will last under those conditions of runaway starter?

 

At the starter should only be three wires, the battery positive cable, the purple wire and a yellow resister wire. What was the fourth wire?

 

The wire that piggy backs on the Bat terminal , then goes up to the horn relay/junction block. I’m not that great of an electric schematic reader, but I think that is on there ?

 

This is a conundrum - I have no idea why either the illustrator or the designers shifted position of the second red (power) wire (from the horn relay junction block) between 1971 & 1972, but you are correct in ascertaining there are, in fact, four wires into the starter in the official 1972 Oldsmobile Chassis Service Manual and three wires into the starter in the official 1971 Oldsmobile CSM (yet, there are only three "posts" to receive the wires on each starter).



1971 CSM Wiring

1972 CSM Wiring

 

That is odd that they decided to go through the starter to get the bat hot to the rest of the car. I thought about just running like the 71 but didn’t know that was how they did it.. The 72 pos bat wire from M and H actually has that 2nd wire built in to the ring terminal

 

1971 has the same horn relay "feeder wire" from the positive battery cable terminal. I think the 1971 and 1972 schematics Norm posted are showing the same thing in regards to the feeder cable going to the horn relay, but the 72 one is a bit confusing way to show it.

That BAT terminal on the solenoid should only have the positive battery cable terminal. You will have a purple wire on the S terminal and a yellow wire on the R terminal.
If you have one of those mini starters. which has two terminals and no R terminal, then you will either abandon the yellow wire or use one of those diode setups on the yellow wire and hook it up to the terminal with the purple wire.

 

Agree they both have the same shuttle wire; yet, IMO, the illustrator got it wrong. It makes no sense to shuttle that circuit from the starter solenoid (as illustrated in 1972) to the junction block.You can easily shuttle (+) from the battery to the junction block. Illustration SNAFU

 

exactly!

 

Equally archaic is to reference a distribution/junction block as a PTO (Power Take Off)....and, this was 1971 (see the 1971 CSM). Most would look at you with deer eyes wondering where in the world would you find a PTO under the hood? Most would look for the PTO exiting the rear of the vehicle!

 

Tomayto/tomahto...

 

And, I agree witchya....propeller shaft/drive shaft...

 

Soooooo. I guess the 100 k question. Any problem with leaving it pigtailed to the big hot starter bolt? Also check out this cable. It appears they have this to go directly do the horn relay in one nice application. No pig tailing?

 

If it was me, I would get a use the cable with the shorter horn relay feed (pictured on this 1971). if the 1972 cable is really as the schematic Norm provided, that is crazy, going twice the distance to come back to the horn relay post.

 

That cable should work perfectly.

 

The delta in cable "style" is necessitated by the difference in location of the junction block/horn relay between 1971/72. In '71 the relay/junction block is mounted on the fender while in '72 the relay/junction block is mounted on the fire wall.



1972 PIM Battery Cable Routing

 

I am guilty in not having provided more information from the beginning regarding the battery cable routing & delta in junction block location between 1971/72. Originally I believe the question was regarding the wire locations on the starter which I provided a diagram earlier. As the discussion developed it moved into battery cable routing with four wires (versus three wires). I provided the wiring diagram for both years. Had I provided the 1972 PIM illustration this would have been more evident earlier in the discussion. Apologies.

 

The 72 horn relay apparently moved from the fender well on the left to against the the fire wall high… a little right of center.

 

Thanks, Norm, I mistakenly believed that the horn relay was also on the fender in 1972; that was why the routing made no sense to me.

 

In case another poster should have a similar question regarding battery cable(s) routing between 1971/72....