The problem with the crd glow plug circuit is the software, not the glow plugs. I have done much sw R&D, and actual bench testing to fix this problem in my crd.
Easy fix is to simply increase the pulse in the software. Don't ask me byte locations and needed values, it's proprietary info. I did this and works great with 7v etecno's.
Its also possible to build a simple pulse generator to supply a 5v adjustable pulse to the gp relay that is dash controllable. I did this for bench testing to make sure I didn't burn out the gps during cold testing. They gotta burn red not white.
Disclaimer Note: If you inject voltage input/signals to active circuits, make sure you incorporate diode protections (debouncers/attenuators etc) so you don't back-feed/surge/fry ecu driver hw, and don't forget voltage multipliers/dividers, etc. when mixing signals. Don't forget circuits can easily latch on too (drivers share grounds with neighboring circuits). Ask me how I know ;-((
If you can locate 12v gp's from old crd applications, simply supply 5v constant to gp relay and get constant 12v relay output. This can be done with a pushbutton for custom applications if needed. Many of my customers do this on BEW/BHW/BRM tdi conversions so they can use 12v gp's and not worry about the ceramics or crappy steel gp's. The existing wires can also handle the 12v currents for short periods without worry, however front end circuit protection needs to be increased.
This is the same gp strategy from bosch used on tdi's that I applied to my crd. I spent over a year modifying the BEW gp problems that plagued tdi's, until corporate released their updated gp strategy recall from all the complaints.
For example;
5v gp pulse -
http://www.youtube.com/watch?v=MsAshsh-VTw7v gp pulse -
http://www.youtube.com/watch?v=JvYbUrhRfaAPlease don't ask me for details, I don't freely give out proprietary engineering data that I have worked so hard to acquire. Remember, it gets passed on the the end user, so that future R&D budget is available for next years tuning challenges.
The sw mods are more than a few edits, it requires many changes in mappings for; cold/warm/hot open and closed loop running controls, along with ambient/engine temperature and elevation compensations and afterglow. If done incorrectly, the plugs can burn out in short time, and you can hurt the engine with death rattle. This is another set of startup parameters that benefit improved startup timing and fueling changes that accompany the gp changes.
Jeff