Help me figure out why truck won't start...Please

[Money Maker]

Changed my batteries and while I had the dielectic grease out decided to apply some to all the connectors for the FASS and Edge. Well now the fuel pump won't cycle and the relay has a steady tapping sound. Truck will not start either.



I diconnected the relay and used a test light to determine that the red wire from the FASS wiring that goes to the female connector for the old fuel pump has a flickering signal. I put a jumper on the relay connector to see if the relay was bad and now the truck will start but because the relay is diconnected the FASS pump has no power and the truck starves for fuel. I put a jumper in the connector for the pump and it will run.



I am not sure if that signal coming from the power supply for the old pump is supposed to flickering like that or not. My guess is no but don't know where to go from here. I don't think changing the relay is going to fix this problem but maybe I am wrong.



Any ideas?????

 

[Money Maker]

Forgot a couple things



With the relay plugged in and the key in the on position the fuel gauge shows empty, voltage 0, oil pressure and water temp gauges don't budge.



With the jumper in the fuel is full like it should be, voltage shows 14, and the other 2 react to the key being turned on and off.



Btw these are the factory gauges

 

[Money Maker]

Well with no other ideas I went and got another relay to give it a try. Results were nearly the same just the taping from the relay wasn't as loud and now there is a taping sound coming from the FASS and it isn't cycling when I switch the key on.

 

[Alan Reagan]

Moneymaker,



Dielectric grease does not conduct electricity. That's probably your problem. Use denatured alcohol to remove the grease and that should make your connection good again. Normally it is used on potentiometers and other sliding contacts. If the connection doesn't displace the grease when you plug the connector ends together, you may be getting a high enough resistance to cause relay "chatter" because the voltage in the relay coil is not high enough to actually pull the relay in solidly.



Dielectric grease is used on connectors, relay sockets, etc, but again, the grease has to be displaced and the connection has to be metal to metal with dielectric grease.



Hope this helps.

 

[Money Maker]

Hope this helps.

Let's hope it does. I'll start cleaning.

 

[Buffalo]

Alan Reagan,



What purpose does dielectric grease serve, then? I always thought it insured a quality electrical connection & kept corrosion away.



I'm not trying to 'challenge' your opinion. In fact, it appears that you may have 'forgotten' more than I know on this subject.



Thanks for your input.



Joe F. (Buffalo)

 

[Money Maker]

Well your right... . dielectric grease does not conduct electircity very well I don't understand why a grease made to put on connectors wouldn't conduct enough for me to at least get a signal through it.





However it did not fix the problem. Truck is still doing the afore mentioned problems. I went through all the fuses checking for something simple. I discovered that when I pull #3 "ingition-run only" the same tapping sound can be heard coming from the injection pump. The signal is a steady pulse that cycles about 5-10 times a second.



Don't know where to go from here. I'll try disconnecting the Edge but I don't think it is the problem.

 

[Pawpaw]

I wouldn't say the grease doesn't conduct electricity, but it is a poor conductor.



It's true benefit is that it forms a barrier that keeps air & moisture out of the connection. No air (oxygen) or moisture... no corrosion.



It works great on batteries. Take the connector off and thoroughly clean the connector and battery terminals. I even scrape & wire brush everything enough to expose nothing but shiny, new metal. Then glob the stuff liberally over all of that exposed metal.



When you tighten the clamps on the battery terminals, most of the grease will be squeezed out from between them, allowing a good connection.



Leave a thick coat on all the metal, but wipe off any excess that would eventually cause a mess.



Bob

 

[Alan Reagan]

I wouldn't say the grease doesn't conduct electricity, but it is a poor conductor.



It's true benefit is that it forms a barrier that keeps air & moisture out of the connection. No air (oxygen) or moisture... no corrosion.



It works great on batteries. Take the connector off and thoroughly clean the connector and battery terminals. I even scrape & wire brush everything enough to expose nothing but shiny, new metal. Then glob the stuff liberally over all of that exposed metal.



When you tighten the clamps on the battery terminals, most of the grease will be squeezed out from between them, allowing a good connection.



Leave a thick coat on all the metal, but wipe off any excess that would eventually cause a mess.



Bob

Most of what we use on aircraft is none conductive but your are correct in that at best it is a poor conductor. Dielectric grease is used to keep out oxygen and thus reduce corrosion. Dielectric is used in order to avoid signal bleed or power bleed between pins (hence, non conductive). It is a great heat transfer medium and is often used on the base of surface mount transistors at heat sinks to help cool transistors.



Back to Moneymaker's problem, it almost sounds more like a ground problem if it is not the Edge. Poor ground will cause the fluctuation you are describing, also.



Sorry I had you clean the connector for nothing. Had the connection points been poor, that might have solved your problem.

 

[Money Maker]

Ok Edge has been disconnected from power, MAP, Fuel pressure, and data link. Still have the same problem. The data link connector has two conntacts that have the same pulsing signal according to my test light.





Is there any chance that some kind of crash kill switch could be activated? My truck was towed home on my wedge trailer that has an angle of about 10 degrees and up some hills that are pretty steep, 8%. Added together it wouldn't be hard to exceed 40*. It was on the back of the trailer where the bouncing is most severe and we accidentally left the ignition on for the journey home. Just wondering????

 

[Money Maker]

Sorry I had you clean the connector for nothing. Had the connection points been poor, that might have solved your problem.

No need to apologize. I was worried that maybe the grease was causing signals to jump pins, so I was thinking about cleaning it off anyway.



Thanks for the help thus far guys.





That signal seems to be everywhere there is anything to do with the fuel system. That has got to narrow down the possibilities.

 

[Pawpaw]

Back to square one.



1. Have you checked for codes?



2. Have you checked all fuses?



Bob

 

[Money Maker]

I checked all fuses in the fuse box under the hood.



I can't seem to get the key on-off 3x's thing to do anything. Even if there weren't any codes it should turn to --------- and then say "Done" but I can't get it to do that. But the factory gauges aren't acting the way they should and I wonder if that is preventing the self diagnose feature from working.

 

[Money Maker]

Ok with the jumper wire in I am able to get a couple of codes



p 0483 fan speed

p 0541

p 2509

 

[DonFitzwater]

Take both of your batteries and have a core pile load test performed... ... A few trucks here this winter experienced the same issues with no starting and clicking relays, no dash function either... ... ..... dealer had to reprogram the truck to the security key fob to run. Hope this makes sense... ... ... . Too much coffee this am!

 

[Money Maker]

Take both of your batteries and have a core pile load test performed... ... A few trucks here this winter experienced the same issues with no starting and clicking relays, no dash function either... ... ..... dealer had to reprogram the truck to the security key fob to run. Hope this makes sense... ... ... . Too much coffee this am!

Pile load test?? does that mean hook them together and load test?



Reprogram the truck to the security key fob??? whats fob?

 

[Money Maker]

P 2509-powerdown data lost error



Seems suspect to me. passanger side battery was out of my truck for a week while making other repairs. It was dead anyway. Driver side was removed and replaced 2 days ago while the passanger side was just replaced yesterday. There was a period of time where there wasn't a battery in at all. I was hoping it would clear some codes that have been on there awhile.



I'm going to go borrow an ohm tester. . we'll see if that will do for me.

 

[Money Maker]

anyone know what pins on the ecm connectors supply power and ground?

 

[Money Maker]

pin #28 of the 50 pin connector has a rapid flickering signal. Not quite as consistent as the pulse i have detected in much of the system but deitnally there. The voltage tester is jumping around from about . 07-. 60 volts



I would't have expected to find anything jumping around, is this possibly normal or is it the problem?

 

[Money Maker]

Voltage tester shows fluctuating power 8. 4 - 8. 6 volts coming from the factory lift pump power supply connector.