86 2.5l no crank

[tmaxx411]

Hey all, I have an 86 2.5l 2wd that HAD the 904 3 speed trans. It was periodically giving me issues starting, figured the starter was on the way out. Not long after, the trans dumped all its atf(unrelated issue).  I swapped a ax5/np231 combo out of a wrangler in, and bought a new starter. However, there is not even an attempt to crank.  If I short the starter with a screwdriver, the starter motor spins, but the solenoid doesn't engage. I'm lost, help me.

 

P.s. There is a 3 wire harness from the old trans. Yellow wire is 12v positive, grey/white wire is reverse lights. Not sure what the black/white wire is. Tried connecting it to 12v, no change. The ax5 only has a reverse sensor

[zomeizter]

With your "screwdriver" test you can get the starter motor to engage because you are bridging the battery lead terminal to the starter motor terminal. Try bridging the battery lead terminal to the small starter solenoid terminal and see if the solenoid engages. Some starters have two small terminals on the solenoid, one is to engage/energize the solenoid and the other is to supply full power to an ignition coil while cranking, you may have the wrong small terminal connected, check it out.

[tmaxx411]

Update: replaced the starter relay, same issue. It will start if I jump the solenoid (small terminal) to the battery, and run fine. But turning the key to start does nothing still

[zomeizter]

Time to verify that the ignition switch is actually energizing the stater relay/solenoid. Ensure the clutch pedal switch is good if it is equipped with this, you can bypass it by bridging both of its terminals.

[dasbulliwagen]

Makes me wonder if the solenoid is looking for a park or nuetral command from the trans before energizing the starter solenoid. Maybe thats what the wires from the trans are. You would have to look up a wiring diagram to be sure of this. Might just be a matter of jumping those wires so the solenoid get the proper complete circuit. 

[Jeep Driver]

On 8/1/2018 at 4:16 PM, tmaxx411 said:

Hey all, I have an 86 2.5l 2wd that HAD the 904 3 speed trans. It was periodically giving me issues starting, figured the starter was on the way out. Not long after, the trans dumped all its atf(unrelated issue).  I swapped a ax5/np231 combo out of a wrangler in, and bought a new starter. However, there is not even an attempt to crank.  If I short the starter with a screwdriver, the starter motor spins, but the solenoid doesn't engage. I'm lost, help me.

 

P.s. There is a 3 wire harness from the old trans. Yellow wire is 12v positive, grey/white wire is reverse lights. Not sure what the black/white wire is. Tried connecting it to 12v, no change. The ax5 only has a reverse sensor

Run the black/white to ground, see if that completes the start circuit. 

[Jeep Driver]

Also-

Run a jumper off the solenoid, tap the other end of the jumper to the POS side of the battery, if the starter spins but does not engage- check battery cables or battery is dead. 

[tmaxx411]

I've tried putting 12v to the black/white wire with no luck. Every so often I get half a crank from the key, and then it cuts out. Almost like a power/ground issue. 

 

Currently it's running via a push button switch in the cab.

 

Having had the 904 3 speed, that is a 100% mechanical automatic transmission (no tcu). 

[omega_rugal]

bad ignition switch? pretty obvious