Puppy boy

Engine wire harness1970 442 auto,about 4 inches from the coil I have two green wires that branch off to a black plug this is about 14 inches long.There is some kind of a resistor that someone has installed in the back of the plug but i don't know why or what its for.I have checked the wiring diagrams but can't see them good enough.
Thanks in advance Rick

joe_padavano

The plug into the solenoid for the transmission controlled spark system.

Puppy boy

I have the three ports right by the oil fill tube with no electrical connection .other posts indicate this may be a 71 ,72 thing.would my harness have the wires and plug that were not used,and why would some one have installed a resistor in the harness plug.Thanks All

joe_padavano

Go back and look at the drawing that I posted. The 1970 solenoid does not screw into a coolant port, it bolts to a bracket. That plug connects to the two terminals on the solenoid. This is what the 1970 TCS solenoid looks like.

oldcutlass

The resister is there for back EMF suppression. It dissipates the current load when the circuit is turned off.

Puppy boy

Very good info, but not done yet.Joe your drawing says except AC,I have AC, Should the 3 port behind the oil fill tube be removed with the solenoid installed.And are the available ,the one in the picture looks very shiny.
Thanks again

joe_padavano

That was the first drawing I grabbed. Given that you didn't tell us the car has A/C, the mind reading thing still isn't working.

The fact remains that the two wire connector plugs into the solenoid valve that I posted. Feel free to crack open your 1970 Chassis Service Manual and do your own research on vacuum line routing. The 1970 system used separate solenoid valve and thermal valve. The 1971-72 cars integrated the two into a single unit that screwed into the coolant port and had the solenoid built into the top.

Puppy boy

Sorry about not including all of the pertinate information .I'm new to the forum ,and didn't me to stress you out,maybe you should take a few days off.
I guess if every body had a service manual we would need such a forum.
Rick

oldcutlass

I wouldn't bite the hands that feeds you information.

rocketraider

Puppy, if you don't have a factory 1970 shop manual it needs to be on your list. There's amazing stuff in them and will help you and anyone else understand and service your 70. Gotta remember things have changed after 50 years and finding people who worked on these cars back in the day ain't easy.

But yeah, the resistor is factory, to reduce radio noise. Oldsmobile used windshield antennas starting 1970 and they were doing all kinds of weird things to eliminate radio noise and static. Would have been simpler to have stuck with a mast antenna...

oldcutlass

The resistor has nothing to do with noise. The factory used filter capacitors on electrical items that generated noise,

rocketraider

Look in your 1970 Service Guilds and TSBs.

Puppy boy

Thanks Rocket i will be ordering a service manual.Just picked up the car so i haven't made my first part order yet.

rocketraider

Get an original 1970 printing if you can. You might pay more but it's a better quality book than the reprints. Reprints lose detail especially on the color wiring diagrams.

A Fisher Body manual helps too along with any other factory issues service literature.

A Motor's or Chilton's Professional Trades Edition general service manual that covers your year is often helpful on troubleshooting and unit repair. Has to be the PTE. Those are what a general repair garage would have used.

We'll help you any way we can because we've all been there. But the internet doesn't have all the answers and depending on the source is often just flat wrong. Hopefully you haven't found the OldsFAQ yet. Joe P and others have been trying to correct its many inaccuracies but that's like Sisyphus rolling his stone uphill.

Puppy boy

Thanks for the good info on the service manual.

Cutlass Fan

Oh yes we would! It is invaluable but doesn't answer all questions.
does the resistor connect to the coil? If so the resistance wire may have failed and been replaced with a Chrysler style resister. I did that on my 72 back in the day.

oldcutlass

Has nothing to do with this thread or conversation, totally different subject.