this is all i know
Tranny is in and out of limp mode
had shop look at it quick, could not leave it had to go ,their results in that quick check was no error codes, But thinks there was no power from red wire (#87) from tranmission relay (click fig. below)

On way home tranny now stays in limp mode
So now at home start to look for problem, check relay, relay is good,
red wire from relay to tranny, good
changed speed sensor on tranny for new
in the mean time need truck, buddy says put jumper in transmission rely from #30 to #87 in above fig.
Does work for when i need truck ( so what ever makes the tranny relay switch,or close whatever you want to say, must be the problem?)

back to search forums for problem like mine
find post what looks to be same kind of problem https://www.dieseltruckresource.com/...98#post2266398
now did the test from that post
now the orange wires with black tracer are #11 and #20 at the PCM
test shows #11 at 36.0 ohms #20, nothing

so I'm assuming I have this same problem bad solenoid in tranny, otherwise #20 should show 36 ohms
am I correct ? someone that really knows please.

 

It would help to know what year your truck is.
Somehow I get the feeling you should be in the 24 valve forum.

 

it is a 1998

 

oh sorry, yes it is a 12 valve

 

i should watch how i say this The # 20 wire I said shows nothing, it shows out of range,