Wait-to-start light issue

[twopipes]

At 30 degrees my WTS light should remain on for at least a few seconds. However it goes out with the other dash lights. And I am not getting the bump in my FASS fuel pump when the key is first turned to on.
Any ideas? Worked perfectly a month or two ago

 

[DonFitzwater]

Sounds like a PCM problem to me. Time to break out a volt meter......and also test the temp sensor.

 

[Kf6cmp]

Mine started doing the same thing. I live in southern California so warming engine is not as crucial, but eventually my ecm went out. There was a short in the the wires to the engine heater. That's my story for what it's worth.

 

[Missouri Mule]

The temps are getting a little down here
( glad I do not live in thd north east) but if come in about 7 to 9 pm and it gets down to 40 maybe be few degrees colder my pre cycle does not come on but the post cycle does. And I will say Mule is acting like an old person with knobby knees knocking against each other if I do not let the pre cycle finish before I fire whim up.

 

[Jerry Wirth]

My wait to start light quit working after changing the heater core. I can change it without disconnecting battery. The dash had bumped the ECM plug, but that was not the issue.
I disconnected the batteries to reset the ECM
I waited for a while after turning the key on until the WTS light came on.
Then I waited until it turned off to start the engine.
Every time I started the engine I waited for the WTS to cycle.
In about a day it was coming on soon after as I turned the key, but I still wait for it to turn off.
The more times I started it and waited for th eWTS, the sooner the WTS light came on, and now it is nearly immediately after I turn on the ignition.

I wonder if by not waiting for the WTS that I taught the ECM to not turn it on?
Everything is working fine now.

 

[GAmes]

The wait to start light on a 12 valve is controlled by the air inlet temp sensor. I imagine yours is too. Testing procedure is in the FSM
https://www.genosgarage.com/product/sensor-3408345/electrical-sensors-2

 

[Jerry Wirth]

Mine is a 99 24v. I believe the ECM reads the manifold temp and sets the WTS cycle accordingly.

What perplexes me is that after I reset the ECM it seems to have learned the WTS differently

When i first bought the truck a few months ago the WTS never came on. Then I had a the first of three heater cores fail and the WTS began working after I had disconnected the batteries. The owner said he just waited for the dash warning lights lights to go off when he turned the key on and started it. It was hard to start in the cold without the WTS

The manifold heater solenoids were bad, so when the WTS light began working I fixed them and they worked. But I mostly never waited for the WTS to cycle unless it was very cold ambient temperature.

But I don't know if the ECM learns the WTS or not. It just seems like it did.