1986 Grand Wagoneer solenoid wiring questions

[909Hemi]

Hi Guys! Thanks for having me
I bought a 86 GW 360/auto. The solenoid wiring is goofy... the guy told me it was when I bought it; Leaving all the wires attached drains the battery quickly. The 2 green wires sharing 1 connector has a ground on it, as does the 14Ga. black wire... which has a cut-off green wire on the same conn. . How do I solve this, and which of the smaller side terminals are "S" and "I"?
Thanks in advance; Frank in SoCal

[will e]

Hi Frank and welcome to the forum.

The "s" and "I" terminals stand for 'Start' and 'Ignition'.

Under normal operation when the key is turned to the crank position the 's' terminal is energized, this closes the solenoid and the starter turns over the engine.
The "I" terminal is connected to the coil. The "I" terminal also has power when the engine is cranking. The reason for this is to make sure the coil gets enough volts during cranking. Normally the coil gets power from an ignition circuit that includes a resistor wire that drops the voltage. During cranking the starter draws so much power that the voltage available drops to 9 volts or so. Power from the "I" terminal does not have a resistor in place and gets all of the available voltage to the coil.

[tgreese]

Hi - Do you own and know how to use a multimeter? The small terminals should be marked S and I on the plastic housing. If not, the S terminal goes through the solenoid coil and grounds to the base of the solenoid. You should measure a very low resistance from S to the base. I believe the I terminal is internally connected to the big terminal for the starter cable.

All the solenoid does is bridge between the two big terminals. If you get the big cables backwards, the solenoid will still work - though with the I terminal connected to the starter side, the ignition will be on even with the key off. Seems unlikely, since I;d expect the engine would not shut off if those cables were backwards.

Also - the battery cable side of the solenoid is a convenient place to attach whatever accessories might need power with the key off, like maybe driving lights. It's also where the charge wire from the alternator connects to the battery. The charge wire goes to the big bulkhead connector on the firewall and up to the dash where it feeds all the dash and the lights. It then goes through the ammeter, back to the bulkhead and to the solenoid, where it connects to the battery. Anywhere along that routs, if you have a load connected in, it will drain the battery.

I suggest you read the '85 GW wiring diagram here. https://oljeep.com/gw/elec/GW_wiring.html Usually when stuff like this is messed with, most of it is still there and will match the diagram. The colors and sizes of the wires will be there, along with the components laid out on the schematic in generally the location they are on the Jeep. You really need the car in front of you to diagnose a problem like this - take it one wire at a time, and use your multimeter or test light.

[909Hemi]

Thanks for the answers! My replacement solenoid is un-marked, but the tip about one of the side terminals being grounded will help me identify it. Yes; I do own a VOM, a crimp kit, and even a Tone/Trace set. I'm a retired Phone Man (I+R), and I'm familiar with tracing low voltage systems. The link to the wiring diagram is something I have been looking for a LONG time too!
My '85 only has 108,000 miles on it, and came with $5,000 in engine and trans receipts. It had been sitting a long time and just needs my love I'll get this solenoid issue sorted... and then it's on to the 4 non-working power windows!

[tgreese]

... one of the side terminals being grounded will help me identify it. Yes; I do own a VOM, a crimp kit, and even a Tone/Trace set. The link to the wiring diagram is something I have been looking for a LONG time too! ...

You mean one of the small terminals. The side terminals are bridged by the solenoid action. There is a copper disk inside that bridges the side terminals when the solenoid is activated. It's a relay, and the S terminal is the relay coil that grounds to the inner fender. Looks like you have it covered.

[nograin]

The factory wiring diagram for '84 (which also covers '85) can be a pain to figure some of the circuits on.
When you work with it, keep in mind instead of connecting everything to the 1st battery illustration, they duplicate the battery in other sections dealing with other circuits. Same with some other items.

You can use the schematic on my webpage for the basic power and starting arrangements.
http://www.heritech.org/wagoneer/mggw5.html

On an '85 it is not a good idea to add any auxillery equipment to the battery post or the solenoid.

[letank]

here is the 85 for color match , you seem to be missing the starter wire which is light blue on the greenish side going the S terminal. The I terminal is the red/white to power the coil directly

SolStarter85BroFSJx.jpg

[letank]

Here is an 86 with the different colors for the solenoid wiring the Red/white is Green/White and the blue as defined by the TSM is now green.
But you can spot the 2 green with eyelet going onto the battery post looking similar to yours -This one is almost unaltered- My 85 is modded with a large amp fuse not shown in the pict

you can spot the S terminal label

SolStarter86DSLfsjx.jpg

[nograin]

Those are good photos.
It does look very possible like the OP's photo is showing an '86 wiring arrangement.
Very different.
For that will need new fusible links.

[909Hemi]

CORRECTION: (I'm the OP) My GW is a 1986. I would'nt have thought this would make any difference at all, but as one poster noted "1986's are quite different"