86 Ford F250 starts by jumping solenoid help me troubleshoot

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  #1  
Old 09-07-09, 07:24 AM
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86 Ford F250 starts by jumping solenoid help me troubleshoot

I have an 86 Ford F250 manual trans that is not starting.
I had trouble with it in the spring, & by cleaning up the starter solenoid terminals, it worked the few times I used the truck this summer.
Now, again it won't start normally. The battery is fully charged.
If I turn the key, I hear nothing.
If I leave the truck in neutral, & put the ignition key in run, I can start the truck fine by jumping the 2 large terminals on the solenoid.
How do I determine what's broke?
#1 the steering column mounted ignition switch.
#2 the clutch operated interrupt switch
#3 the solenoid
#4 something I missed
Thanks!
 
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Old 09-07-09, 07:29 AM
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Try jumping "Hot" to the Small terminal at the solenoid.....I believe it should be a red wire with a blue stripe ..That ends with a rubber elbow at the solenoid
 
  #3  
Old 09-07-09, 08:29 AM
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If you have volt meter or 12v test light, check that you are getting power to the small connectors on the solenoid. If you get power and nothing happens, the solenoid is bad.
 
  #4  
Old 09-07-09, 08:30 AM
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Ok,
with the ignition switch in the run position, I jumped hot from the battery terminal to the small terminal on the solenoid.
The truck started & ran.

I'm guessing that means the problem is elsewhere?
 
  #5  
Old 09-07-09, 08:39 AM
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Ok...Next.....

Look at the clutch interupt switch......

The wire from the ignition switch is white with pink dots, and everything after the interrupt should be Red w/blue......It is also possible that an "Interrupt relay " exists, but for now, what colors are at the clutch switch??

As mentioned a Simple automotive "Test Lamp" can be used to check wiring and find the "LOST START SIGNAL" ......
 
  #6  
Old 09-07-09, 10:23 AM
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Ok,
The clutch interrupt switch, both wires going to it are red with blue stripe.
I had trouble pulling the disconect plug off the switch, so I unbolted it from the truck to get better access.
I stuck a 12 volt light tester on one of the interrupt switch plug terminals.
When I turned the ignition switch to the start position, the tester lit up.
Then using a piece of wire I jumped between both terminals of the plug, & started the truck.
So !! I thought bad clutch interrupt switch! easy fix!
But then I tested the switch for continuity with a meter, & it appears to work...rats!
Maybe I have a bad corroded connector into the clutch switch?
I am tempted to just cut it off & crimp the wires togeather & see if that permanently solves the problem.
(safety police note, this truck is not on road, it is my farm snow plow firewood buddy)
 
  #7  
Old 09-08-09, 06:19 PM
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Originally Posted by valsound View Post
Ok,
with the ignition switch in the run position, I jumped hot from the battery terminal to the small terminal on the solenoid.
The truck started & ran.

I'm guessing that means the problem is elsewhere?
when the key is in the start position, it sends a 12 v. signal to the relay to energize the electromagnet which picks up a large bronze washer which sends the full 12 v. and amp. from the batt. to the starter which turns the engine over. at the same time there is 12v. to the dist. to allow the vehicle to run. releasing the key from the start pos. lets the sol. drop back out leaving only the 12v. to the dist. to keep it running. sounds as if there is no 12v. signal to the sol. with the key in start pos.. with key in start pos., have someone check for voltage at the sol.(small wire) where you jumped it. back track from there if no voltage.
 
  #8  
Old 09-09-09, 04:50 AM
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If it works fine with the clutch interupt switch jumped then I would replace it.
The problem with a continuity test is that it says that electrical current can pass. It does not say how much current
The path foward thru the switch could be the size of a pin and the continuity would read 0 ohms and yet the draw of current needed when starting truck could require a 16 gauge wire or more.
I would do a volt drop test or just replace the switch.
If it continues to work with the "test wire" then it must be that switch.
 
  #9  
Old 09-09-09, 06:18 PM
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I understand what you mean about the clutch interrupt switch showing continuity, yet not being able to pass enough voltage to work. (I didn't think about that before)

Right now, I have cut off the connector & crimped the wires togeather. So far for 2 days the truck starts.

But because of the previous intermittent nature of the no start, I'm going to let it go this way & see if it keeps working.

Murphy dictates if I put a new switch on, another short will be the real problem.
 
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