I have an F350 that won't start. I bought a glow plug relay on eBay with manual switch and I might of fried something so I put another one on. There's 12 volts on the constant post but when I put voltage meter on ignition post and turn the key instead of it jumping to 12 volts it tops out around .9 or 1.0. Also yesterday when i went to start it the relays under the dash were going ape ****. Both batteries are good, the test from autozone on alternator showed good but possible issue w internal regulator although when I turn on lights it works fine. Any help would be greatly appreciated. Is it possible I fried the injector module??? PLEASE HELP!!! THX

 

Welcome to the site..

Generally when the relays chatter like that it's a system low voltage indication.

As a start point, check fuse 64 in the CJB. S/B Battery voltage Y/N ?.
64 feeds the ignition switch for its input power distribution, when in Run/Start the ignition switch then inputs power into the PCM power relay,, which when it closes its contacts is the switched input power distribution for the injector Driver Module. If the voltage is low on 64, batts are known hot,, could be the connector on the CJB or a least part on the checks before moving forward-CJB although would affect the CJB globally..
If the glow relay shorted it may have blown #22 in the CJB
Load-glow distribution for the glow relay output shares voltage for the alt harness/cable,

 

I swapped the relay with spare. Not the issue.
So a little more info. The relay is supposed to get 12 volts on ignition post once key is on, yet it doesn't. Also tried hooking up OBDII and it wouldn't run diagnostic test. There is oil on the IPC sensor I ordered a new one since I seen oil is sure sign it's bad. Since all of this happened I can tell while cranking it's not even trying to start like it's not getting fuel and the check engine light is on. Soon as the sun comes up I'm going to try and run through a handful of test I seen on YouTube that seem pretty straight forward. I just bought this truck from my uncle who always kept it plugged in for it to start in the morning. They had cracked fill cups so I had to change those out. Thanks for the help

 

oh I'm going to check those fuses as soon as I can get to it I was going through them yesterday and they all seem to be pretty good

 

A little side note;
As you know, there have been all sorts of problems with the windshields leaking on those years and it caused all sorts of problems due to water intrusion on the fuse panel under the driver's side of the dash. It wouldn't hurt to check behind that panel for corrosion. It also managed to get into the GEM module.

 

The 'rattling' relays may be a flag if it's still present. (?)
When you mention 'relay' it's a bit confusing if your talking about glow control, starter solenoid/relay or CJB units.
If you had a voltage drop at the CJB it would most likely affect most all that it protects.

The 7.3 needs 500lbs 'minimum' of high pressure oil during cranking on a start, if not, the injector Driver Module won't fire the injectors.
It also needs a minimum of 150 RPM during cranking. Slower, and it won't start.

A bleeding ICP certainly a wise fix, but may/may not be cause.
Cracked 'fill cups'?

 

k that would suck. I'll check it.
I have more info now that I'm possibly understanding what happened.
So on top of the truck never start unless it was plugged in I purchased a relay online with the manual switch the directions from the guy on eBay (possibly bad advice) said to run a short wire from the constant 12 post to either of the small posts on the side of the relay and on the other small post limit to the switch and then ground the switch out if I have the small jumper wire running from the 12 volt switch to the "I" on the relay that makes the relay under the dash click if I switch it around the other way it's quiet but still doesn't start. I'm wondering if I grounded out the plugs and burned them up seeing how it np longer starts plugged in. I'm trying to avoid a pricey diesel mechanic who will probably add a ton of **** then hold my truck hostage. Then again maybe they are honest. This is my first diesel

 

Depending on the current AM /ambient temps outside, the truck should still start (or sound like its trying) if temps are mild although may require some extended cranking without glow assist.

The glow plugs/control are activated by the key, but the active glow ON times are subject to engine oil temps, BARO, so even if the 'wait to start' is out, the plugs may remain hot. 131*+ and they won't activate.
Usually you'll see the 'load' of the glow plugs or draw indicated on the trucks cluster charge gauge. When the plugs are switched off, the rate of charge will jump up...

My .02 on a manual/switched glow control is not a good idea. If left ON it would add more stress/heat to the UVC (under valve cover) harness's as well as shorten the glow plugs service life. As well as the glow relay. The glow plugs are protected from charge system/batteryover voltage, if a switch is used, that protection is gone..

Fuse #64-30 amp needs to test good (checked with a light or meter, not just visibly) as it supplies voltage into the ignition, then when the key is in Run/Start voltage inputs into the PCM power relay (also check fuse 22-20amp) which in turn supplies voltage into the injector driver module.

The PCM is in control of the 'ground' on the glow relay. Ignition is switched on power/voltage as you noted, but if you add power into the PCM connection on the glow relay you create the potential to damage it.

The 'Ign' connection on the glow relay is actually a input feed off of the PCM power relay (fuse #22 is circuit protection if the glow relay shorts) which like mentioned, gets its power from the ignition/#64..

If you can do some pin point checks with a test light, it may help in a direction to go, or prove out some power distribution points..

If the glow system is deactivated ( if the glows are active it can flame out of the Intake) it should start on a 'short shot' of ether.. Ether is tough on the engine, NOT to be used in concentrate or often, but may help to rule out fail possibilities..

 

Ok let me check. The plug relay has a forced switch so no chance of being left on but I still suspect that as a possibility due to bad wiring. I'm good with doing away with it. My ford manual doesn't have a #64 fuse but I checked 22. Going thru them now. If pcm module is damaged would dash still work ? I also tried starter fluid and it will turn it over I almost get the impression like it's not getting fuel

 

I'm going through these fuses now and when I turn the ignition on the fuel pump fuse doesn't light up with my light tester nor does it sound like it's kicking on is that mean bad fuel pump or faulty connection somewhere my phone's charging why I checked this all be back thank you