CarTalk.com Blogs Car Info Our Show Deals Mechanics Files Vehicle Donation

‘93 F250 starting issue/wont start

Folks, need some ideas because im missing something.

My ‘93 F250 just won’t start when I turn the key. I don’t even get a whir or anything. No engine feedback. Dash does it thing, where the speedo drops and the mileage gauge goes blank. Im very sure its not the battery. It’s exactly a year old Interstate Mega-tron. If i try to normally jump it, still nothing. BUT, if I move the positive jumper cable to the fender solenoid, its starts. Just needs the key in the on position. No clutch being pushed in. I tried disconnecting the safety switch and that didn’t change anything.

Here is what I have done as of late (all new parts)
-new battery, new alternator, belt, spark plugs, spark plug wires, distributor and cap, new starter, new fender mounted starter solenoid, new clutch master cylinder and safety switch, some other new wiring as it was damaged and caused a charging issue.

All I can think of is to test the grounds and wires. Take a multimeter to it and see. Ill check the fuses too for good measure.

It runs and drives mostly normal. I have a temp sensor thats going screwy but thats the only oddity.

Is there anything else I should check while im at it?

-1993 Ford F250 XLT 351w/5.8L w 5-speed manual for reference.

Perhaps you wired the starter relay incorrectly, switching the wires on the smaller terminals?

I certainly won’t rule out the possibility. But as a Collision repair tech, ive learned to label everything and take photos to line it up correctly again. So I doubt it but I will check it again.

That’s called a “no-crank” in mechanics language. Probably the most common problem reported here. Measure the voltage at the two starter terminals with the key in “start”. Both should measure at least 10.5 volts. What do you measure? Probe directly at the starter, between the terminal and the starter case. Everything connected. Running 3-4 foot test leads from the starter to the volt meter is ok for making the measurement easier.

If both measure 10.5 volts or more, replace the starter. If either measures less than 10.5 volts, work backwards towards the battery to find out why.

BTW, disconnecting the clutch safety switch will usually guarantee the engine won’t crank. That switch has to be bypassed to remove it from the circuit for testing purposes

My 93 was a rust bucket, I would check the ground connection from the battery to the chassis first. Loved hat Granny gear for plowing, usually started out in second
!

1 Like

How about the ignition/starter switch at the base of the steering column?

https://www.rockauto.com/en/catalog/ford,1993,f-250,5.8l+v8,1124648,electrical-switch+&+relay,ignition+starter+switch,4700

Tester

1 Like

That might be a good place to start, if mine was tilted all the way low the front left turn signal would not work! Tilt it up and bang on it it would work again! Yes maybe try changing the tilt and beating on it and see if it works!

Huh okay. So… on that note, how do i bypass the safety switch? Because Once I pulled the connection off and the I went to wiggle* it a touch and it broke.

*and I mean gently, us techs may not seem like it, but we are actually gentle about disassembling things.

Tilt the starter or steering column?

I will have to check it. I got a rebuilt one 2 years ago when the old one went out.
Rebuilt steering column and all the componets.

Change the tilt on the steering wheel, my ignition lock was so bad you did not even need a key to start it.

re: clutch safety switch

from what I’m seeing that switch is actually a gang of three switches, which all are supposed to close when the clutch pedal is pushed. What the other two switches are used for, don’t know, the input to the first switch is 12 v w/key in “start”. when that switch is closed that results in 12 volt applied to a r/lb output wire from the switch which powers the coil of the starter relay, which causes the relay to close and that powers the starter motor S terminal. The starter motor B terminal is connected directly to the battery +, so when the S terminal is powered that should cause the starter motor to spin as long as both S and B are at least 10.5 volts (as posted above).

On my Corolla the clutch safety switch is just one switch, so bypassing it is pretty clear what that doesn. On your the situation is more complicated, so bypassing without knowing what the other two switches do isn’t a good idea. Instead measure the voltage at the starter relay control terminal. It’s a r/lb wire and should be close to battery voltage with the key in “start” and the clutch pedal depressed.

Ah ok. Ill do some digging and see. But either way, thats a 6 month old part. And boy is it not fun to deal with. I’d rather be without it and with it.

I looked at the vids on youtube, it looks like you just take a couple of the wires and fuse them which essentially bypasses the switch.

That’s how it works on my Corolla, but there’s only 2 wires on the connector for that car. Your clutch switch connector has more wires to worry about. If I understand the wiring diagram correctly, it will never crank if that connector isn’t connected. If you have a problem with the clutch switch it will show up with the voltage measurements at the starter I posted above.

Gotcha. Ill review the wiring diagram and hookup the multimeter to it and see if I get 10.5v. If not, well…

I have also heard the auto tranny trucks have a bypass of their own, an end cap/block sort of thing. Would that work rather than screwing with the wiring?

From what I see the automatics are wired for the clutch switch, but of course there’s no clutch pedal for them, so there’s a bypass gadget that is installed in place of where the clutch switch would have connected. It shorts out each of what would otherwise be all three clutch switches. The safety switch for automatics is the shift lever (or park/neutral) position switch. IOt’s just a single pole/single throw switch. That switch is in the manual’s wiring too, but is replaced by a jumper cable from what I see, effectively bypassing it for automatics. Whether installing that bypass gadget on a manual car would work or not, it seems like it would, but don’t know with any certainty.

Hmmm. Any idea besides a junk yard as to where to get one?

I have one nearby but really don’t like going there when its been snowing every weekend with highs in the single digits.

try surfing over to LMC truck’s website.

Any idea which one it is? Because honestly I don’t know. My truck is 4x4 so maybe #1?

I can get one cheaper via rockauto but it looks like the C6 auto tranny switch is the proper fit but they don’t show the plug for it so im not entirely sure.

Neutral safety switch/range sensor.