When I turn the key on my 2008 F350 6.4dsl i hear the relay click but engine does not turn over.If i turn key on and unplug the black plug by left battery and jump male side to positive the truck star

Will the engine not turn over at all ? Any recent engine repairs ? How did it run before this occurred ?

Engine cranking, did you check for spark at the plugs, also, check fuel injector pulse. Any applicable trouble codes?
When you first turn on the key, no crank, can you hear the pump run for a couple seconds?
If only a fuel issue, jump the relay to see if pump will run. Unplug relay, use jumper wire between terminals 30 and 87, the pump should run, don't need to use your key. As you can see, terminal 30 is hot all the time. Also, check that fuse.
Let us know what you find?

You say, no voltage? I presume you mean at the glow plug terminal when the key is operated by an assistant? If so, look at the fuse box but also the current is heavy so check the relay as well. Some have a timer built in or a relay plugged into a separate control box. You should be able to hear it click when the key is turned.

It's likely a bad glow plug relay found on the left fender well. You may have bad glow plugs as well. You should hear a faint click when you turn the key to glow psn. . Open the hood and have someone glow it. The click should be abvious and the wires will run from the relay to the glow plugs. also obvious.

I copied this from my GM service manual for 1982 6.2 diesel.

1. If the glow plug relay is not clicking on and off then turn the ignition to the RUN position and connect a 12V test light to ground and touch the pink/black wire in the glow plug relay connector.

2. If the light is off repair the open cicuit in the pink/black wire to the splice.If the light is on then touch the light blue at the glow plug relay connector.

3. If the light is off replace the glow plug relay. If the light is on, disconnect the connection at the thermal controller and touch the black wire in the connector.

4. If the light is off, repair the open circuit in the light blue wire from the thermal controller to the glow plug relay. If the light is on repair open circuit in black wire back to a splice. If no trouble is found replace the controller.



You should also get your hands on this Haynes book. Diesel Engine Repair Manual, part # 10330. Excellent coverage on the 6.2 and 6.5. In it, they say that early 82\'s have a hole at the number 2 hole on the pin connector of the wire harness for the thermal controller. this allows dirt in there and corrodes the pins. Remove the connector and clean thoroughly the pin area on the connection and controller. Seal the hole with some silicone. If things are still acting up, replace the wire harness connector.



Hope some of this helps.

What size engine ? The clicking you hear is probably the starter relay , provided you hear the click while turning the key to the start position . That black box is the fuse / relay junction box. Testing the starter electrical circuits with a volt meter is the way to find the problem . Voltage drop testing . Free wiring diagrams here http://www.bbbind.com/free_tsb.html Enter vehicle info. Year , make , model and engine size . Under system click on engine then under subsystem click on starting . Click the search button then the blue link.Does your vehicle have a manual or automatic transmission ? First blue link for a manual transmission ,the second link for a automatic transmission .
How to voltage drop test starter motor circuit

VEHICLE RELAYS Operation Diagnosis

check maxia fuse under hood and relay

Have you checked for power on the fuel shut-off solenoid on the injection pump? There are two wires to the pump. One is the fuel shut-off the other is the cold advance. Both should be hot with the key on when the engine is cold. Do you hear the glow plug relay clicking when you turn the key on?

YOUR TURN SIGNAL RELAY HAS GONE BAD. SOME WHERE UNDER THE DASH YOU WILL FIND THIS. FIRST TURN ON YOUR RIGHT TURN SIGNAL AND LISTEN VERY CLOSLEY UNDER THE DASH YOU SHOULD HEAR A CLICKING FIND THE CLICKING AND YOU WILL HAVE THE FLASHING RELAY THE OLDER ONES WERE ROUND THE NEWER ONES ARE ROUND.

Ive never seen a car start up just fine after leaving the key on all night. I would try jumping it. If the voltage is too low it wont start.