I have a 1997 ford F350 WITH A 7.3L DIESEL, it turns over but will not start. My wail to start light or other indicator lights do not come on when I turn on the key.

Your glow plug relay is located on top of the engine in the middle area. there is a removable access cover where it has the 7.3 logo. check for voltage at the glow plug relay. it looks alot like a starter relay on the fenderwell, with the 2 big contacts. Those will get corrosion on them and the posts will break out of the bakelite housing. Should be a corresponding fuse for that circuit in the buss box under the hood on the fenderwell. that is the first place you should look.

The first thing to do is locate the owner manual.

Look for the glow plug relay MAIN FUSE location.

The glow plug portion of your van is not working.

This difficulty scale from 1 to 10 is a 9.

You will need a DVM and tool undo the cables to each glow plugs.

It's a 1 to 2 hours troubleshooting job.

I'm going to fire off a quick list

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Check / replace blown glow plug relay main fuse
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Disconnect each center nut of the glow plug wire. PLEASE CHECK ONE AT A TIME.

Read the resistance between the center of the glow plug and the metal base of the plug.

Please take good note on each glow plug resistance reading.

MAKE SURE all cables are put back and tighten properly.

Compare the resistance on all cylinders.

OPEN/high resistance is bad glow plug.

In general 3 ohm or less is OK.

You should buy one and use its value as baseline.

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Glow plug relay can be bad.

You will need the VOM and a friend to turn the key.

Check the voltage to each glow plugs. It should be 12.6-13.6 volt.

Be careful,the plugs will get HOT.

Compare the voltage on each cylinders.

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So the problem can be combination of

glow plug relay

glow plug relay main fuse

glow plugs

ignition switch is unlikely but I'm going to list it anyway.

Once again,this is a difficult and time consuming job. I will ask a friend to help out,

Good luck.