My glow plugs do not start to heat for about 1 minute after I turn the key. If I turn the key and wait (regardless of the Wait To Start light) there is no power drain indicated on the instrument cluster until about 1 minute. If I try to crank before that time, even when it is not that cold (like today when it only got down to 37 and it is 51 right now when I tried to start it) it wouldn't start unless I let it cycle for over a minute. After I see that the glow plugs have finished heating, by the return of the volt meter to the previous level, it starts right up.

This winter I changed out all the glow plugs (3 bad ones), the harness was intact and I also have a new Glow Plug Relay. I replaced the near-death starter 2 days ago with a much better one and it cranks like a house on fire now.

My question is: Could this be a problem with the Power Control Module? Doesn't the PCM control the glow plug operation? Can the PCM be re-programmed?

Any thoughts are appreciated.

Thanks in advance.

 

Bump...

Still looking for any advice on the PCM. Thanks.

 

Here's a crude outline of how the glow plug system works on the PCM side of things.

1. The PCM looks at two sensors to determine if glow plugs should be energized or not. The main part of this equation is the oil temp. sensor. If the oil temp. is below 131 degrees.....it will fire up the glow plugs. This sensor may be your problem.
2. The next sensor it looks at is the barometric sensor. This determines how long to keep the plugs energized.
3. If the oil temp. is above 131.....it will do a "bulb check" of the WTS, but will not turn on the plugs.
4. One last thing.....the PCM will protect the plugs if it detects abnormally high battery voltage. I'd have my batteries "load" tested.
Hope this helps.