E7 no start

[Gravelguy413]

So now my truck won’t start. E7 fully mechanIcal. Turn the key and the relay gives a single click. Batteries are up. Left key in on position and jumped relay with screw driver still would not roll over. Is this a bad relay or something in the starter? 

[Rob]

When you say relay, are you referencing the relay in a junction box, or magnetic switch mounted to the starter? Jumper the one on the starter itself which is what everyone calls a "solenoid" which it actually, is but it's actuated by a magnetic contactor, or switch.

Post up a photo of where you are trying to "jumper". Post one of the electrical end of the starter motor also where the battery cables and wiring connect.

[Vladislav]

There are actually 3 relays. One below the dash. One somewhere under the hood or a cab depending the truck is conventional or cabover and the last (and the largest) is the starter solenoid which carries a double function being both a solenoid to put the gear into the flywheel and a relay to connect starter's power contacts.

What I would do is jumpering each one of them. The 2nd one is what to start from since usually it's accessable (mounted on the firewall on R's and CH's) and operates reasonable currents so jumperng it with a screwdriver wouldn't make much fireworks. If the crank starts spinning you look for anything wrong in the cab. If not your way is to investigate the starter.

[Gravelguy413]

The truck is a 96 RD. I was jumping the relay which is mounted under the hood on the firewall just above steering column. Anyway I took off the cables that lead from this relay to the starter solenoid and cleaned everything up and tried it again. The relay on the firewall clicked like before but then it started on the 3rd try.  Last summer the truck did this on several occasions, would not start on the first turn of the key but would on 2nd or 3rd try. Not sure if this is an ignition switch problem, a starter relay problem or starter solenoid or actual starter problem. Any ideas?

[Joey Mack]

the firewall selenoid has 3 large wires on one post and 1 larger wire by it self.   put a test light on the large single wire post, it should not be lit at this time... turn the key to start and then the light will light, if not,  check the little wire for the key signal. if its a 4 post check the small ground post wire for a good ground to the cab. most of them are 3 pin selenoids that are self grounding. if still no power on the single big wire after this test, R+R the selenoid.. jojo

Edited February 13, 2021 by Joey Mack