Glow plugs i have a '97 ford f-350 7.3L power stroke, need to change glow plugs and nener have worked on a diesel moter and dont know where the glow plugs are please help

generic p1391 is CMP or CKP Sensor Signal Intermittent Conditions.
p1391 code Ask com YouTube Search this link is codes more for chrysler ---the following codes pertain to your vehicle p1393 is Glow plug circuit low input, bank #2 (left) Open/short/miswired circuit, ... ---- p1391 is Glow plug circuit low input, bank #1 (right) Open/short/miswired circuit, faulty relay, glow plugs.
An Introduction to the Power Stroke Glow Plug System this link will explain and assist in repair

Does it have dual batteries? A friend of mine threw 3k$ at his, then found out one of the batteries were low or had a bad cell. It was turning over for a long time, and we never suspected them being at fault. Like 2 750 or 850 CCA batteries. Have yours tested at a parts store to rule them out.

You should never use starter fluid when the glow plugs are hooked up. It can cause severe engine damage. You probably need to replace all the glow plugs and the glow plug controller.

If you can't pull the codes from the pcm it has either died or lost it's ground assuming it has power. I would try to get a wiring diagram and check both the power and the ground for the computer itself, because it is what turns on the pump and the wait to start light.

I know for some models that Ford had another Diesel timer for the glowplugs for severe weather. This timer was meant to keep the glowplugs on longer.

I had an 87 Ford Diesel and the top wires on the timer were tight and clean. For some reason when I loosened them and retightened the wires the timer worked better.

Many truckers use a Diesel additive and usually the fuelstops have modified Diesel for cold climates. I understand there is a Cetane rating for Diesel and Premium Diesel may help.

As I understand these systems the ECM is not what powers the glow plug relay. Any kind of engine controls happen after the engine starts.

There should be a power relay which feeds the juice to the glow plug relay. When you turn the keyswitch to start and the light for the glow plugs goes out you should hear a clicking as the glow plug timer cycles juice to the glow plugs.

The glow plug side is a separate system from the fuel management side. Someone should check the glow plugs to see if each is good. The diesel system used to be simple and it sounds like you are complicating what should be a simple repair. I could be wrong, but it does not sound like the Dealer is selling you the parts you need.

A diesel needs a heated combustion chamber to initially fire and then it runs by compression. Perhaps if you change the power relay from the vehicle you removed the ECM from and tried it in your truck it would work with your old ECM.

Sounds like bad advice. If your glow plugs are bad, the last thing you want to do is try to start it. Remember, diesel engines use these glow plugs like coils in a toaster. Since diesel is harder to burn than gasoline, the glow plugs heat up to a combustible temperature, allowing the diesel to ignite and your vehicle to start. I don't know the reprocussions of trying to start it without them working...but it can't be good.

It sounds more like the glow plugs, the older models had trouble out of the module, but the 6.0 is pretty safe from all those problems. And don't forget to use the correct fuel additive for diesel engines, it helps .

The relay should cost about $35-45. A common Ford Starter relay can be used in place of the official glow plug relay. All that is required is a relay with terminals that have 5/16 or 3/8 terminals and can carry about 150-200 amps. When all 8 glow plugs turn on, it draws about 150 amps is all. There are two relays for the 7.3 diesel. One energizes the glow plugs and the other energizes a heating element in the air intake. That one is used to help eliminate white smoke while warming up and is turned on and off by the engine computer. It is usually only called for when the temperature is 20 degrees F or lower.
Otherwise only the glow plug relay works.

The root cause of your concern may not be solved by the block heater more than likely you have some bad glow plugs or and bad glow plug relay, also which engine is it? 7.3 or 6.0 some 6.0 have a block heater but no cord