Hi

Upon start up, the "wait to start" light comes on for three seconds. Do
the glow plugs remain on any longer after the light goes out?. My service rep states, that the glow plugs will remain hot until the two variables are achieved. Barometric pressure and oil temperature are reached. If you could find the specs on the "wait to start" sequence, that would be very helpful.

The powertrain control module, is it directly responsible for these operations?

Thank you

1996 F350 7.3 PSD

 

i believe the glow plugs will cycle for two minutes after the ignition is turned on, when its cold i usually let my cycle for about 30 seconds or a minute and she starts fine.

 

Correct. On time is up to 120 seconds max.
EOT commands length of time.

Bill

 

From the Factory service manual:
Same as what these guys are telling you.

Glow Plug System

<META content="Glow Plug System" name=tps_proctitle>

The 7.3L diesel engine uses a glow plug system which preheats air in the combustion chamber to improve cold engine starting.

The system consists of eight glow plugs, the glow plug control module (12B533), powertrain control module (PCM) (12A650), engine oil temperature (EOT) sensor and barometric pressure sensor (BARO sensor) (12A644).

The glow plug system is electronically controlled by the powertrain control module. The powertrain control module energizes the glow plugs immediately after the key is placed in the ON position and then determines how long the glow plugs will be on according to the engine oil temperature and the barometric pressure. The required time for the glow plugs to be energized decreases as the engine oil temperature and barometric pressure increase.

The glow plugs are self-regulating, and the powertrain control module controls relay ON time. The powertrain control module protects the glow plugs by energizing them for short durations if the battery voltage is abnormally high.

 

Watch your battery/amp gauge. It will drop alot while they are cycling and jump up when they turn off. You will be able to time it if you want.

 

If my EOT is listed as 540F
and baro is at 14.7 psi.

is the EOT within acceptable ranges

 

That can't be right.
Did you get this info from a scanner or measure the volts/ohms at the EOT?
Do you have a check engine light on?

If your oil temp is that high the CEL should be lit and the oil turned into soot.

Engine oil temperature less than 74°C (165° F) or above 116°C (240°F) will turn on a CEL.


<TABLE cellSpacing=0 cellPadding=3 border=1><TBODY><TR><TH vAlign=bottom align=middle>k Ohms </TH><TH vAlign=bottom align=middle>EOT (Volts) </TH><TH vAlign=bottom align=middle>°C </TH><TH vAlign=bottom align=middle>°F </TH></TR><TR><TD vAlign=top align=middle>1.19 </TD><TD vAlign=top align=middle>0.53 </TD><TD vAlign=top align=middle>120 </TD><TD vAlign=top align=middle>248 </TD></TR><TR><TD vAlign=top align=middle>1.56 </TD><TD vAlign=top align=middle>0.67 </TD><TD vAlign=top align=middle>110 </TD><TD vAlign=top align=middle>230 </TD></TR><TR><TD vAlign=top align=middle>2.08 </TD><TD vAlign=top align=middle>0.86 </TD><TD vAlign=top align=middle>100 </TD><TD vAlign=top align=middle>212 </TD></TR><TR><TD vAlign=top align=middle>2.80 </TD><TD vAlign=top align=middle>1.09 </TD><TD vAlign=top align=middle>90 </TD><TD vAlign=top align=middle>194 </TD></TR><TR><TD vAlign=top align=middle>3.84 </TD><TD vAlign=top align=middle>1.37 </TD><TD vAlign=top align=middle>80 </TD><TD vAlign=top align=middle>176 </TD></TR><TR><TD vAlign=top align=middle>5.34 </TD><TD vAlign=top align=middle>1.72 </TD><TD vAlign=top align=middle>70 </TD><TD vAlign=top align=middle>158 </TD></TR></TBODY></TABLE>


<TABLE cellSpacing=0 cellPadding=3 border=1><TBODY><TR><TH vAlign=bottom align=middle>k Ohms </TH><TH vAlign=bottom align=middle>EOT (Volts) </TH><TH vAlign=bottom align=middle>°C </TH><TH vAlign=bottom align=middle>°F </TH></TR><TR><TD vAlign=top align=middle>7.55 </TD><TD vAlign=top align=middle>2.11 </TD><TD vAlign=top align=middle>60 </TD><TD vAlign=top align=middle>140 </TD></TR><TR><TD vAlign=top align=middle>10.93 </TD><TD vAlign=top align=middle>2.56 </TD><TD vAlign=top align=middle>50 </TD><TD vAlign=top align=middle>122 </TD></TR><TR><TD vAlign=top align=middle>16.11 </TD><TD vAlign=top align=middle>3.01 </TD><TD vAlign=top align=middle>40 </TD><TD vAlign=top align=middle>104 </TD></TR><TR><TD vAlign=top align=middle>24.25 </TD><TD vAlign=top align=middle>3.44 </TD><TD vAlign=top align=middle>30 </TD><TD vAlign=top align=middle>86 </TD></TR><TR><TD vAlign=top align=middle>37.34 </TD><TD vAlign=top align=middle>3.82 </TD><TD vAlign=top align=middle>20 </TD><TD vAlign=top align=middle>68 </TD></TR><TR><TD vAlign=top align=middle>58.99 </TD><TD vAlign=top align=middle>4.13 </TD><TD vAlign=top align=middle>10 </TD><TD vAlign=top align=middle>50</TD></TR></TBODY></TABLE>

 

Cuda

I think that has to be 54.0*
The sensors could be good if amb temp was in the mid 50's, and your at sea level on the barrow.
Best way to check barrow is to get into from weather station (air port best).
The pressure will be in hg's. You have to conver hg's to psi for the pressure.

Bill

 

Yep Bill something is wrong with the temp he posted....54F is more belivable. Most scanners will not compute our EOT and other sensors particular to our diesels correctly. Maybe the newer ones are better??

 

Hi

ya the oil temp readings are incorrect. A decimal was missing 54.0degrees

Thanks for the information

 

The truck was in because of a failed Powertrain controwl module PCM. After the replacement the "wait to start" light would come on for three seconds. The Fords last check of the WTS light system reads as follows.

Check and report for the wait to start light only stay illuminated for three seconds. PCM was replaced.
Correction: Scan for codes
pass data logger
Glow plug lamp 3 seconds
Glow plug relay time 60 seconds
EOT 580 F
Baro 14.7 psi
Cannot go back to previous PCM callibrations

The location of the vehicle is Vancouver BC Canada sea level