7775 won't crank

[rwhitwo]

Been working this a problem for awhile. Working through diagnosis flow from manual. Red wire into key switch shows 12 volts, but 0 volts on white wire going to run/service switch whether key in run or start. Replaced key switch - same problem. Checked grounds seem to check out good. Tested continuity on run/service switch and checked out okay. Stumped please help.

 

[Mike10]

The white wire should be on the center terminal which is the start terminal. The red wire should be on the batt terminal of the switch. White wire will only have power in the start position.

 

[rwhitwo]

The white wire should be on the center terminal which is the start terminal. The red wire should be on the batt terminal of the switch. White wire will only have power in the start position.

Mike10- Thanks for the quick response. The key switch is wired just as you described, but when turned key to start now voltage on white wire. Replace key switch with same result. Replace white wire between instrument panel, key switch, and run/service switch with no change. I am so confused. Is there a problem downstream of the key switch on the white wire that would prevent voltage from key switch exit? Could the run/service switch be bad, even though the conductivity passed?

 

[Mike10]

Mike10- Thanks for the quick response. The key switch is wired just as you described, but when turned key to start now voltage on white wire. Replace key switch with same result. Replace white wire between instrument panel, key switch, and run/service switch with no change. I am so confused. Is there a problem downstream of the key switch on the white wire that would prevent voltage from key switch exit? Could the run/service switch be bad, even though the conductivity passed?

Check your voltage at the battery terminal of the switch when trying to start. I believe you will find you no longer have voltage there either. The most common cause is dirty connections at the battery or a battery that is defective.

 

[rwhitwo]

Check your voltage at the battery terminal of the switch when trying to start. I believe you will find you no longer have voltage there either. The most common cause is dirty connections at the battery or a battery that is defective.

Glad the Forum is back up. Still a problem. I replaced the battery connections and the voltage does not drop on the battery terminal when I turn they all the way to start, but still no voltage on the white wire leaving the switch. It is hard to believe that the new ignition switch I bought would also be defective. I will disconnect wires and check the continuity with the key turned next, but I am truly stumped.

 

[Mike10]

Glad the Forum is back up. Still a problem. I replaced the battery connections and the voltage does not drop on the battery terminal when I turn they all the way to start, but still no voltage on the white wire leaving the switch. It is hard to believe that the new ignition switch I bought would also be defective. I will disconnect wires and check the continuity with the key turned next, but I am truly stumped.

Did you check if you had 12v at the red wire at the switch when attempting to crank the engine?

 

[rwhitwo]

Did you check if you had 12v at the red wire at the switch when attempting to crank the engine?

yes and it was 12 V while cranking

 

[Mike10]

yes and it was 12 V while cranking

If you have 12v at the red wire while attempting to crank and no power at the white wire, then there are only two possible problems, one the red wire is not on the batt terminal, also assuming the white wire is on the start terminal, of the switch or the switch is bad, there is no other possible reason for no power at the white wire. Even if there was a dead short on the white wire, it would affect the voltage on the red wire also and should blow the 15a fuse in the engine compartment.