Do you have any other codes? There are a bunch of things that can throw a GP light.
Test the glow plugs between the tip and ground, it should be between 0.5-1.5 ohm. Too big of a difference will throw a code. Corrosion on the plugs, tips, or connector will throw a code. If you find corrosion on the harness or bad wiring then I would replace the glow plug harness.
A possibility is a bad coolant temp sensor or plug. The GP are only supposed to go off below a certain temp. If the coolant temp sensor doesn't sense this, the GP won't go off. Look behind the flange coming off the driver's side cyl head, same place as the 2002's sensor. Unplug the sensor (don't remove unless you are prepared to a hot coolant shower) it to trick the ECU into thinking it's cold and it may help.
There is also a fuse on top of the battery plate.
Lastly, your hard starting issue could be a fuel leaking out preventing pressure, low battery voltage, clogged fuel filter, a shorted wire somewhere along the line., etc. And glow plugs do age and get weaker over time. The pumpe duse glow plugs are ceramic unlike the pre pumpe duse and are also more fragile so handle them with care.
Test the glow plugs between the tip and ground, it should be between 0.5-1.5 ohm. Too big of a difference will throw a code. Corrosion on the plugs, tips, or connector will throw a code. If you find corrosion on the harness or bad wiring then I would replace the glow plug harness.
A possibility is a bad coolant temp sensor or plug. The GP are only supposed to go off below a certain temp. If the coolant temp sensor doesn't sense this, the GP won't go off. Look behind the flange coming off the driver's side cyl head, same place as the 2002's sensor. Unplug the sensor (don't remove unless you are prepared to a hot coolant shower) it to trick the ECU into thinking it's cold and it may help.
There is also a fuse on top of the battery plate.
Lastly, your hard starting issue could be a fuel leaking out preventing pressure, low battery voltage, clogged fuel filter, a shorted wire somewhere along the line., etc. And glow plugs do age and get weaker over time. The pumpe duse glow plugs are ceramic unlike the pre pumpe duse and are also more fragile so handle them with care.
