289 M 1975 Peterbilt battery cable problem

I was looking more at this photo. Is that aluminum frame or are they just painted silver?

Just from the pics I was thinking it was worth more than 19k?

I was also questioning the Battery/ Voltage set up given the vintage. But when he said everything worked I suspected 12v. Didn’t look like the battery box was set up for 4 batts which from my limited vintage experience most 6 volt series ran 4 batts.

Keep us posted.

 

The OP says it starts and runs well on 5 connections or 12v. 12 will not spin a 24 volt starter.

If it still had a series parallel switch or solenoid actually is what they are the start button would have a diode in the wire to engage the solenoid and give the starter 24V. If it was still on a series parallel set up the starter would never engage if you jumped it with a button or wire it will hang engaged due to low voltage. I agree it’s of the right vintage. The 6 volt batteries were also more narrow than a 12. However if it was 24 again 12 would not crank it. Not only was the starter motor itself 24 but the solenoid to engage it.

So the best advice given has been trace the cable back and see where it goes. Is it possible it still has a parallel switch absolutely. Not everyone deletes unnecessary equipment in a change over. It’s also easy to get confused on where a jumper was or wasn’t etc. I’ve seen it multiple times in a battery change. Sometimes by so called mechanics. Thing to remember here is it’s starting on the current 12v

 

@Goodysnap is probably correct in post #2 but it would be best to verify.

Positive is red and goes to the starter solenoid which sits on top of the starter. This is for 12v with no series parallel switch.
You may have a starter relay which looks like this. Connections go from the battery to the relay then to the starter.

OR this.


Series parallel switch looks like this.

 

I was wondering the same about the frame, but have only seen that in KW.

Anybody know if Pete did an aluminum frame?

OP, if you're not sure, you could you post a pic of the inside of the frame at the back. Easy to tell there

 

I’m certain it was an option back then for Pete. A quick search says that they were. I have also seen FLDs late 70,s early 80s with them also.

 

Delete, already covered.

 

I have an 89 pete that has/had an aluminum frame. It is now cut into pieces and used for lowboy blocking!

 

Good to know. I've only seen it on 70's KW's.

@Oxbow, is that the frame you just replaced? I remember the pics you posted of the frame were crazy

 

Yes it is. We bought a rolling chassis configured almost idenically to ours, except steel frame. Pretty much plug and play when swapping the cab over for the most part. Identical wiring harnesses really helped.

 

The mention of SP switches reminded me of the ability to unscrew the cap on the SP switch and push the plunger to engage the starter manually. Kind of a neat option really.