Lift pump & Wait to start light?

[ram head]

My ? is my wait to start light does not come on and my lp does not cycle when I bump the starter,i hooked a code scanner up today and it comes back 0 codes and when I turn the truck off there is a clicking noise coming from my speaker about every three seconds with the key off.

[Mopar1973Man]

Could you help me out? Could you fill out your signature with your truck information. Then I know what you have.Both the Wait To Start and the Lift pump are Internal ECM problems. Yo could try taking it to a dealer and allowing them to hookup a DRBIII tool and see if there is a diagnostic they can run. But typically the ECM should light the WTS light for a small period of time and the lift pump should be active for a short 1 second burst. There is no lift pump relay. The relay in the PDC is the power relay to the VP44.

[ram head]

Mike it is a 1999 auto 4x4 bone stock nothing else except for fp gage.I don't know why it is not showing any codes like I said the truck starts up fine first thing in the mor. or hauling 10,000 pounds down the road in 99 degree weather and stoping and starting the truck right back up.THANKS

[Mopar1973Man]

Both the WTS light and the lift pump are directly controlled by the ECM there is no other outside device that control these.

[LiveOak]

If you just bump the starter without starting the engine, will the lift pump come on?

[ram head]

Liveoak, no when I bump the starter the lift pump does not come on prime up or run its little cycle I have plugged the truck into my buddys scanner and its not throwing any codes this weekend my fuel gauage line sprung a leak so I replaced it and cracked the injectors 1&3 truck started right up.It fires right up cold or hot everybody keeps saying ecm is bad but I am under the impression if it's bad truck should throw codes and not start.The wait to start light does not come on either.I may take it to dodge and have them scan it just to see what they say I want to figure it out cause I plan on selling it and do not want the next guy to have to worry about it, put new radiator in today and going to put the fuel boss lp on this weekend.THANKS

[LiveOak]

For starters, I would suggest checking the wire that goes to the lift pump from the ECM for voltage when you turn the key on and when you bump the starter. If you have voltage in the range of 8.5 to what ever the max battery voltage is, you ECM is probably good. IF NOT, rather than reinvent the wheel, I believe this topic has been covered here in the past: http://forum.mopar1973man.com/threads/4869-Lift-pump-is-not-powering-up-in-the-on-position In short, you may have to run a relay direct off the battery from a key activated hot wire in the wire harness such as the accessory wire. Hope this helps get you in the clear.

[ram head]

So here's a update went on vacation for a week get back jump in truck go to start it up and the wait to start light comes on so I bump the starter and the lp still does not cycle and truck will not start unless light comes on.

[Mopar1973Man]

If there is no Wait To Start light then the ECM is not booted up and so there is no software to fire the injection pump. So it going to be a ECM issue.

[ram head]

The light is coming on now and I do hear lp priming up,but the truck will not start till the light comes on,and when it throws it's little fit and the light does not come on the truck starts right up.

[98whitelightnin]

I have seen this exact thing on two different trucks and another ECM fixed both trucks.

[Mopar1973Man]

The light is coming on now and I do hear lp priming up,but the truck will not start till the light comes on,and when it throws it's little fit and the light does not come on the truck starts right up.

As long as the Wait to Start light comes on the software booted into RAM and complete without issues and the software starts up by checking the IAT sensor and the need for grid heaters. If there is no Wait To Start light then there is no ECM and it will not start because there is no signal for the VP44 nor is there signal to the fuel pump relay in the PDC to supply power to the VP44. so its a dead truck. The lack of Wait to Start is typically caused by a bad RAM in the ECM and during booting process there is memory errors so the boot up process is dumped and retried till it does boot up properly.