1986 f250 6.9 IDI wont crank.

[Dnest79]

Hello hopefully I can get some help here because I am kind of stumped.

I have a 1986 f250 6.9 IDI that wont crank. I turn the key and nothing happens except the engine temp light lights up and stays on as long as the key is turned and this happens every time I turn the key. I checked the battery, fully charged, checked the solenoid on the fender wall, looks ok, jumped across the solenoid and the engine cranks. So I replaced the starter solenoid and still nothing, no crank.

Could it be the trigger wire?

Not sure what could have happened. I parked it one day and it ran and the next i get nothing.

Any ideas?

 

[gnathv]

Is it auto or manual? Clutch safety switch or neutral safety switch maybe.

 

[gnathv]

Did you jumper 12v to small post on relay or just jump across the 2 large terminals? If you put 12v to small terminal you can verify if relay works, or check “trigger wire” for 12v when key is in start position.

 

[Dnest79]

Its an auto.

i jumped across the large posts=cranked.

tested old solenoid. when i jump to the small post i hear a clunk, guessing that means the old solenoid is still good.
tested new solenoid. When i jump to the small post, no clunk, maybe its bad.

Tested the red wire (small post, trigger wire) with the key in the start position=no 12v.

Could it be the ignition switch on the column? i dont think its the key/ignition because the key starts the coils and all the lights work.

 

[Dnest79]

Is the engine temp light an indicator, is that some kind of old school code to signify a problem?

 

[gnathv]

It could be the ignition switch on steering column. I’ve seen them go bad or get loose and slightly move. Have you tried holding the gear selector up in park or moving to neutral to see if it will crank?

 

[gnathv]

You can also move the ignition switch on column with your hand to see if it will crank.

 

[gnathv]

You’re only seeing the temp light in the start position and not run. That should just be a bulb check. It will not stop the truck from cranking.

 

[Dnest79]

I hooked the old solenoid back up and jumped from the battery to the small post=cranked. So old solenoid is good.

I looked on the column and the ignition switch connector seems loose so i pushed it down, nothing. When i am not pushing down on it, it is a bit loose. I am guessing that means i should replace the ignition switch? This seems to match: https://www.autozone.com/batteries-...tch/duralast-ignition-switch-ls503/763961_0_0

 

[gnathv]

When you heard the clunk on the relay it should have turned the motor over. Did it? The new one that made no sound, was it screwed to inner fender? The mount is what grounds the relay.

 

[gnathv]

Check your neutral safety switch first

 

[Dnest79]

Old solenoid: When I jump the small post it cranks.

New solenoid: ...no it was loose hanging from the wires. i guess its probably ok then.

 

[gnathv]

Most likely it is good. Jumper your neutral safety switch and try cranking.

 

[Dnest79]

How do i check the neutral safety switch? do i check the bit on the trans or the bit on the column.

 

[gnathv]

Unplug the harness at the shift lever switch on the transmission. Put a jumper wire in the connector you unplugged.