99, Hard start when cold HELP!!!

[53 willys]

I have been working on my friends 99 PSD 130,000 miles. It hard starts every morning when cold, I know it's glow plug system related because it fires right up if plugged in.

I don't know PSD well but I knew from a quick look on here to check the GPR so I told my buddy and he just went and bought a new GPR, (napa#GPR110) put it on and it did not fix it I assumed the worst and told him he needed glow plugs...long story short this is what I have checked and changed.

1.Napa# gpr110
2.All 8 glow plugs
3.Cleaned all the Battery grounds
4.had the batteries load tested individually
5.Run a direct ground for the relay housing to the battery-post


with the key "on"
I have had about 11.87v+ at the relay constant. (big post)
I get about the same amount of volts at the small wire on the front most terminal. (PCM signal I'm guessing) Then on the other small terminal there is 0.50 volts for 2min's then it switches to the 11.87v. the relay only intermittently pulls in and powers the other big post(glow plugs) did I get a bad NEW relay??? I put the old stock relay back on and it worked the five times I cycled the key just like it was supposed to. by this time I had run out off time to work today, but I told him to take it home and see if it would start in the morning. I am not completely convinced that it is fixed so I wanted to ask some of you guys input on this thing it's driving me nut's

BTW I did use the search first but I have not found the answers to all this stuff.
Thanks for your help in advance

53
Mark

[klpaul]

Thie info below I pasted over and should answer your questions.

The glow plug system is electronically controlled by the Powertrain Control Module. If the temperature Is below 55°C (131°F) the Powertrain Control Module will energize the glow plugs immediately after the key is placed in the ON position. Then, depending on the readings from the Engine Oil Temperature (EOT) sensor and the Barometric pressure (BARO) sensor, the Powertrain Control Module determines how long the glow plugs will be on.

The glow plugs are self-regulating. If the Engine Oil Temperature is above 55°C (131°F) , the Powertrain Control Module will bulb-check the WAIT TO START lamp but not energize the glow plug relay.

The glow plug ON time varies from 0-120 seconds depending on battery voltage, Engine Oil Temperature and Barometric pressure.

[53 willys]

Thanks for your help but I already knew that

the glow plugs are intermittently coming on when it's 20* outside.
they should be coming on but there not


I have +power constant to the big post Red/black wires.
I have 11.87 volts to the small terminal on the front of the relay(PCM signal)
no volts on the other small terminal toward the back of the engine.
No volts to the other big post black with yellow wires(glow plug wires)
Then after 2 min's the back small terminal gets 11.87 volts.
only intermittently does the relay actually pull closed.
So this means the relay is bad right?? did I get a bad relay right out of the box??

maybe I am explaining it wrong??
come on you PSD techs when I searched before I posted you techs had answered a bunch of these same problems but this truck seems to be different the the others.


calling all PSD techs!!!!!!!!!!! please help......


Thanks Mark