'96 F250 7.3L PSD 4x4

I went out to start it the other morning, and got no response from the starter. Here's what I know:

• The 'Wait to Start' light & all other lights came on & went off as expected, except the battery light, which stayed on
  
• The batteries are fully charged, and there is no corrosion on any of the posts.
  
• I heard all the normal clicks
  
• I can still start the truck if the key is in the ingition in the 'engine on' position and I short out (hotwire) the two main terminals on the starter relay

There's a third, smaller, terminal on the starter relay with a push-on connector on it. I suspect that the wire connected to that terminal is a lead from the ignition switch that's supposed to signal the relay to divert power to the starter, but I don't get any voltage through that lead (not even when turning to the key to the start position).

Here's what I want to know:

Am I right about that third terminal on the relay? If so, I don't think buying a new relay will fix my problem. Since I get no voltage into that third terminal I'm assuming there's a short in the wire connected to it, and the relay never gets a signal to close the circuit to the starter.

I suppose I could just pay the $25 or so for a new relay & find out if that fixes the truck, but I live in the country & don't want to drive all the way to a parts supplier just to pay for something I'm not sure will fix my problem...

Any help would be really appreciated!

 

Welcome to FTE. I believe you are correct about the third terminal. Did you check the wire, and how about the ignition switch itself?

 

it never occurred to me that the ignition switch might be the problem....I'll give that a try first. The cable into the relay is wrapped into other thick groups of wires...looks like a pain to expose it all the way back to the starter. I'll do it today though if the starter seems to be ok.

--thanks

 

If it is the wire, just cut it at both ends and replace it.

 

ok - the ignition switch is fine. The wire from the switch to the relay is also fine - there's no resistance between the switch and the relay. So, it must be the relay, plain and simple. The lowest setting my voltage tester has is 15 V (will pick up anything from about 5 to 15 volts), so I figure the signal sent from the ignition to the relay must be less than 5 volts and that's why I couldn't see it.

I'll post another reply once I get the new relay...

 

OK - bought & installed a new starter relay, and it didn't fix the problem. I'd turn the key to start it and still nothing.

So I knew it wasn't the relay, wasn't the starter (I could still hotwire it), wasn't the ignition switch or the lead from it to the relay. Frustrated I went back to my shop manual's engine wiring diagram to make sure I hadn't missed something.

Turns out I had missed something...the clutch position sensor switch. I looked at it and noticed that the switch assembly had slipped off a small retainer bracket. I put it back on, and bingo, problem solved.

Now the only problem is I have to drive all the way back to the parts supplier to return the relay!