No wait to start

[SAndreasen]

I have no wait to start light what do I need to look foR

 

[DavidC]

I believe it's triggered from the IAT to the ECM. Is it cold enough to trigger it. Does it come on briefly when turning the key on.

 

[BigPapa]

Which truck?

 

[SAndreasen]

3 of 1998 24 valve .

 

[SAndreasen]

I believe it's triggered from the IAT to the ECM. Is it cold enough to trigger it. Does it come on briefly when turning the key on.

No light even with tbe gauge check when i fitst turn the key . Yes its cold enough been below freezing for 3 weeks

 

[BigPapa]

SYSTEM OPERATION
Vehicles equipped with an optional diesel engine have a wait-to-start lamp. The wait-to-start lamp gives an indication that the conditions for easiest starting of the diesel engine have not yet been achieved. The wait-to-start lamp bulb in the instrument cluster is lighted by the Powertrain Control Module (PCM) after the ignition switch is turned to the On position.

One side of the wait-to-start lamp bulb receives battery voltage when the ignition switch is turned to the On position. The PCM switches the ground path for the other side of the bulb based upon several inputs and its internal programming.

The wait-to-start lamp lets the driver know that the intake manifold air heater grid has had sufficient time to warm the intake air for a good quality start. The intake manifold air preheat cycle is controlled by an electronic air heater control module. The lamp will be turned off by the PCM when the heater control module cycle is completed, or if the driver turns the ignition switch to the Start position prior to the end of the heater control module cycle.

Could be:

• Bulb is blown
• Sensor or sensor wiring is bad
• PCM is bad

 

[SAndreasen]

Bulb good . Volt meter does not fluctuate
New iat sensor could be bad as it was a cheap auto parts store junker 90$ Made by standard but i wonder about its quality
If it is the pcm its getting a push button

 

[DavidC]

Took a while to find it and this is from the 99 FSM

Grounds

 

[DavidC]

Wait to Start Light

 

[SAndreasen]

Thanks