Here's a brain teaser. When I turn on the ignition the wait to start light does not come on. It takes ten seconds or more to come on. The engine will not start until the wait to start light comes on. I have a friend with a cummins 5,9 and he too has the same problem. When the light comes on you can hear the lift pump energize and the engine will start. It also brings on the check engine light when this condition occurs. Sometimes the wait to start light comes on with the ignition as it should and the engine will start right away?
Has anyone else experienced this quirk??

 

I've got the exact same problem. Anybody got advice?

 

Alabama, Is yours a 1999 model? It seems this problem is not too uncommon on the '99 model.

 

The ECM mounted on the side of the engine is responsible for illuminating the "Wait to start" lamp. It goes through a self check when it gets a start signal from the key switch.

There are only a couple of reasons the WTS lamp takes a long time. One is the ECM is faulty and when doing its self check it will find a problem that can correct itself after several seconds. The other common problem is the ECM does not receive good 12 volt power and this may be fixed by replacing the relay in the power distribution center (fuse box) on the fender well.

If the problem is in the ECM it may eventually need to be replaced. In my opinion the ECM can become intermittent because of a part on the circuit board failing to make a good electrical connection or just changing value due to many heat/cool cycles. The ECM computer looks for nominal voltage values when it is powered up and if something is out of range will not pass the self test keeping the lamp off.

Try the relay first.

 

Thanks MR. Bentvalves, I swaped the trailer relay with the diesel heater relay and the WTS light comes on as soon as I turn the key. (Like it used to do) Thanks again for your help.