Triton motor, only has 103,000 miles. If it get below 70 degrees, truck won't start. How do I run codes on this '99 truck?

 

You need a scan tool or code reader that is compatible with OBD ll.
. What you might consider is trying to try briefly heating the PCM with a hair dryer. Then if it starts, that would confirm a problem within the PCM (computer).

 

Thanks,I have an OBD2. My Dodge gives the codes without one. Only about 11 degrees, need to let it warm up outside.

 

OBD2 read "no codes".

 

Unfortunately, not all problems yield a code.
That's when you have to fall back on the basics of fuel and spark.
I only suggested the heat trick because there were some problems that were common with some V10s and I thought that might save you some time and expense.
Crank sensors don't always throw a code and usually failed warm or hot, but there can as you know always be exceptions.

 

Think I will try a fuel pump relay. Only about $20 and I hear they can work off and on with temperature.

 

Not my truck yet, I am supposed to inherit it when my in-laws estate is settled, but you never know.

 

Before replacing a possibly good relay,
when you first turn the key on you should hear the fuel pump in the tank run for approx. 2 seconds. If you hear that, relay should be OK.
If not PCM provides the ground to fuel pump relay to operate and give pump the 2 seconds to operate. Depending on what you get will determine where you go from here.

 

This truck has a stupid ignition alarm that sounds when you turn the key. You can hear nothing.