Help truck shut off on highway

[MO'Kelley]

I replied to your PM.



FSS is Fuel Shutoff Solenoid. I wouldn't worry about the boot, just make sure it's jamming the plunger. I ran mine without the boot for a few hundred thousand miles with no issues.

Thanks, for the info, Your suggestion ref the relay paid off, I found a youtube video on how to check that relay, I checked it ( by jumping the circuit) and behold the solenoid pulled up. Heading to parts stor to find a replacement.

 

[MO'Kelley]

I replied to your PM.



FSS is Fuel Shutoff Solenoid. I wouldn't worry about the boot, just make sure it's jamming the plunger. I ran mine without the boot for a few hundred thousand miles with no issues.

UPDATE:, I found on youtube a way to check the relay by jumping the 2 main red heavy duty wires. when I did that the solenoid pulled up. So I went to the parts store and got a new relay. Well that didn't work. somewhere i believe the relay is not getting power to activate the relay. I checked the # 9 fuse. its good. Ive looked for a fusable link but can not find it. if its in the PDC, power fuse box how is it labeled. where can I check next?

 

[MO'Kelley]

UPDATE:, I found on youtube a way to check the relay by jumping the 2 main red heavy duty wires. when I did that the solenoid pulled up. So I went to the parts store and got a new relay. Well that didn't work. somewhere i believe the relay is not getting power to activate the relay. I checked the # 9 fuse. its good. Ive looked for a fusable link but can not find it. if its in the PDC, power fuse box how is it labeled. where can I check next?

OK UPDATE:
So what i'm learning it appears that the pull side only works when the starter is engaged, is that correct? If so what steps can i check to test wiring withiout activating the starter, ? thanks

 

[GAmes]

The fusible link comes off the left side battery positive post. The stock ones are blue.

 

[BigPapa]

the pull side only works when the starter is engaged, is that correct?

Yes, that's correct. The relay is triggered by the same brown wire that triggers the starter solenoid.

Here's a diagram of the relay connector and the solenoid connector.

You'll need a helper to bump the starter and see if you get power to the BROWN wire at the relay. If you have power there when you bump the starter, replace the relay and check the center terminal that's connected to the RED/VIOLET wire at the solenoid connector the same way you checked at the relay connector by bumping the starter. If you're getting power to the relay and to the solenoid, you have a bad ground or a bad solenoid.

 

[MO'Kelley]

The fusible link comes off the left side battery positive post. The stock ones are blue.

Thanks , only fusable links i can fine , if what i found is in the PDC , dont see any any where else, im thinking if i can jump the wires i must be getting power,

 

[MO'Kelley]

Yes, that's correct. The relay is triggered by the same brown wire that triggers the starter solenoid.

Here's a diagram of the relay connector and the solenoid connector.

View attachment 128755

You'll need a helper to bump the starter and see if you get power to the BROWN wire at the relay. If you have power there when you bump the starter, replace the relay and check the center terminal that's connected to the RED/VIOLET wire at the solenoid connector the same way you checked at the relay connector by bumping the starter. If you're getting power to the relay and to the solenoid, you have a bad ground or a bad solenoid.

Thanks , do you know exactly where the # 2 wire is coming from so i could check connection , ohms?

 

[GAmes]

Thanks , only fusable links i can fine , if what i found is in the PDC , dont see any any where else, im thinking if i can jump the wires i must be getting power,

The fusible links look like wires that have been connected to wires of a different color. There were three or four of them attached to the battery when the truck was new. None are in the PDC. I'm guessing you don't have a factory service manual, the most used tool in the shop.

 

[GAmes]

The fusible link for the starter is connected to a heavy gauge red wire with a black stripe.

 

[BigPapa]

Thanks , do you know exactly where the # 2 wire is coming from so i could check connection , ohms?

It runs from Pin #87 of the Starter Relay in the PDC to the Starter and the relay connector in the diagram for the relay you replaced on the firewall.

 

[gcorron]

I'd say that many of us have had this problem. Important thing to remember is elementary diesel technology: If it's running, and getting fuel, it should stay that way. Check the FSS first.
One year, the truck wouldn't start. Got out, looked, the FSS was not in the run position.....damn! I had no time to check it for a day or two, so I just popped the hood, pulled up the lever, and no problem. One day in a heavy snow i decided it was time to find the issue. Ordered a new FSS. Running the wires with my fingers and tapped the battery cable with my elbow. Ooops, maybe if it isn't about to fall off, it would work! And did! Idiot, you deserved to freeze to death for a few days!
Sorry I didn't see this a bit earlier, but why should I to be the only one to learn from my ignorance??

George

 

[MO'Kelley]

It runs from Pin #87 of the Starter Relay in the PDC to the Starter and the relay connector in the diagram for the relay you replaced on the firewall.

Thanks , Just getting back to it today, Does the intake Heater Grid interconnect to any of this? I took off the intake to get to the FSS and wanted to check the Heater Grid before replacing hood. I thought if I turned the key on and wait for the Wait To Start light to go out I would be able to feel if the grid heated up. It Didn't . any thoughts, i Will be researching.

 

[BigPapa]

The grid heaters shouldn’t activate above 59*.

 

[MO'Kelley]

The grid heaters shouldn’t activate above 59*.

Thanks ,,,Ok , While I've got access to it, How can I check the Relay for it from the battery? I have 12v power to the fenderside of the 2 solenoids/ relays for the Grid. When I turn the key on no power to the otherside. so something is not sending the signal to activate them, ie its above 59* the 2 side terminals one wire is connectred to each and the other wire has always been disconnected.
are these termainal looking for a ground or power to activate the solenoid? If I knew that I could see if they are working?
i'v tried grounding and applying power to the terminals , the solenoids/ relays will not activate.
thanks

 

[BigPapa]

The PCM supplies ground to the relays. You should have 12 volts on the Light Green/Black wires at the relays ONLY with the key on.