Electrical Starter engages only when crossed on the solenoid

[GreatCJ8]

1985 CJ automatic holley sniper.

No clicking, headlights disengage with ignition turned, unplugged nsf, replugged no difference. Battery maintained via trickle charger, starter Does engage with a screwdriver across solenoid method.. Help
And hi, I'm Mike

 

[TSB8C]

Loose/bad connection between battery->ignition switch->solenoid. There is a large red wire going from your battery across the firewall to the driver side bulkhead connector and up under the dash to the ignition switch. From the ignition switch another light blue wire goes back through that bulkhead connector on another pin and goes to the "S" terminal (start) on the solenoid to engage it when the key is turned to START. When you jump the solenoid from the "BAT" terminal (battery plus connection) to the "S" terminal (start) you are bypassing this circuit going into and back from the starter switch. Now the headlights should dim if they are on while trying to start since the starter will draw most of the battery power temporarily. But if the lights are going completely off, and you are not even getting any clicking of the solenoid when trying to start, the battery power is not making it through this circuit. Check the red wire from the battery to the bulkhead connector and the light blue coming back from it to the solenoid. Check the two pins in the bulkhead connector as this is a common issue with corrosion and "goo" resulting from old dielectric grease in the pins. And check the ignition switch - not the key lock cylinder, but the actual switch on top of the base part of the steering column. Here's a pic of the bulkhead connector showing the pins. Main power from the battery is second down on the left. The light blue to the solenoid is second from the bottom also on the left. Easy test: jumper these two pins with a clip lead or test wire. This bypasses the ignition switch. If the starter engages, pull the connector and check these two pins (both the male and the female sides) and clean as necessary. If that doesn't resolve the issue, then you're chasing wiring under the dash and to the ignition switch. If jumping these pins does not engage the starter, then your problem is under the hood with either the red wire from the battery to this connector and/or the light blue wire from this connector back to the solenoid.

 

[GreatCJ8]

OK, I'm back at it. I bought a new pos cable, no change

 

[Patrick]

Look for 12v “start” signal at solenoid small terminal while trying to crank. If present, then it’s a bad solenoid. If absent, trace back from there.

 

[TSB8C]

When you say you are jumping the solenoid, are you jumping the two large terminals (POS battery cable to large cable going to starter) or are you jumping from the large POS battery cable to the smaller "S" terminal where the voltage from the ignition switch connects to engage the solenoid? See the pic below for reference. If you're jumping across BATT to STR and your starter cranks, you've bypassed the solenoid and you have one of two issues: (1) bad solenoid itself, or (2) no voltage at the "S" terminal coming from the ignition switch to engage the solenoid. If you're jumping from BATT to the "S" terminal, then that is engaging the solenoid and you've proven a good solenoid. So back to the wiring to/from the ignition switch as I mentioned in my prior post. So that's your real test starting point - jump the BATT and the "S" terminals and see if the solenoid engages and the start cranks. If it does, good solenoid and follow my prior recommendations on wiring to/from the ignition switch. If it doesn't crank when jumping BATT to "S", then the solenoid is bad. Voltage applied to the "S" terminal of the solenoid should make it engage, which then internally connects BATT to STR to send juice to the starter. The only other possible issue, which you've already addressed, would have been no/low voltage at the BATT terminal due to a faulty POS battery cable or connection. Obviously you have to have a solid contact from the battery to the BATT terminal on the solenoid to even start with.