Check engine light
will fail to illuminate with the other warning lamps with ignition on
intermittently. When this happens, the truck will crank but will not start. When
the check engine light does come on with the ignition, all is fine. I need to
find out what specifically controls the check engine light separate from the
bulb check relay that turns them all on with ignition initially in order to
track this down. It will be fine for a week or two and then out of the blue-act
up... I already put in a new CPS thinking that was the most likely culprit and
it obviously is not. No wiring diagrams exist on RAVE or in the factory shop
manual I have for some stupid reason. Relays all look good in the right kick
panel although I think most are body related. ECU is dry and plugs look clean.
There are some plugs behind the washer reservoir from the ECU I have not checked
as I do not know which one would be the right one, but expect them to look the
same as the others...

Does the ignition
switch give a signal to the ECM that may be getting interrupted? Not sure if the
ECM gets a ignition on signal and then controls the check engine light coming on
if it gets this signal. No idea what wires to check or what to look for since no
one has a wiring diagram....