FSD replaced, glow plugs don't work

[Dick 48]

94 6.5 turbodiesel pickup
Replaced the PCM and FSD (with heat sink) and she ran fine for a while.... Replaced the alternator when the glow plugs wouldn't lite (yep, bad diodes).
Now the glow plugs will only heat when the battery is 14 volts (and won't heat when it rains!, no dash lit and no click)
I tested the leads and have 12.75 volts to the pink "A" pin and a good ground. Just can't get any voltage on the "B" yellow lead.
It used to do this intermitent after replacing the FSD and PCM, but only after working fine for a couple of months.
It's been a year and I'm ready for something.
By the way, the dealer couldn't diagnose the FSD problem.... got the answer here.
Dick

[More Power]

Pin B on the glow relay is the PCM control line. The PCM uses this lead to command a glow cycle. So, if you're not getting a PCM command, check the interconnecting wire and PCM.

The 1994+ glow system chapter in the T-Guide will show you which leads to test.

http://www.thedieselpage.com/members/guide.htm

MP

[ttpost]

i am having a similiar problem with my truck, sometimes they work sometimes they dont. when they are not working and the engine is cranking the glow plug light will cycle on and off.

i believe mine is the pcm signal also, the yellow wire, i think i have a intermttent open but i havent checked it out yet.

i think i am just going to replace the wire from the pcm to the relay.

i will watch to see what you find out good luck

[MEdlin]

Did you guys ever find out what this problem was?

[ttpost]

i havent repaired mine yet but it is in the connector behind the fuel filter, i had my wife watch as i moved the wires and it would come on. i am just going to solder the wires together and get rid of the connector. what is funny is my glow plugs work when i park facing down hill. so untill i get to it, i park down hill :D

[MTTwister]

ahhh - the undocumented mercury switch!