Diesel engines are fuel efficient and reliable, and they run for a very long time, so long as you take care of the proper maintenance. One downside to owning a diesel car is that it is hard to start when it gets cold outside, and the older the car is, the harder it gets to start. Fortunately, glow plugs were invented to warm up the diesel fuel just enough that even on chilly mornings, the motor would start. When you start to have glow plug problems, you might need to use fresh wiring for the new ones.
Use an adjustable wrench to disconnect the negative connection to the car battery by loosening the nut attaching it. Then repeat with the positive connection. Be careful not to let the connections touch the battery terminals while you work on the car.
Locate the glow plug controller. Find the wires that run from each compression cylinder, and follow them back from the engine to wherever they are mounted. That is the glow plug controller. The wires you followed are the wiring harness for the glow plugs.
Pull up on the wiring harness connection to the glow plug controller and remove it. Use a ratchet to remove the nuts mounting it in place on the engine and set them aside, but be careful not to lose them. Pick it up with one hand, and expose the battery cable attached to the controller. Disconnect the battery cable nut.
Install the new glow plug controller. Attach the battery cable to the controller with the nut, and line up the mounting holes with the bolts where the old controller was mounted. Put the nuts back on the bolts and tighten them with the ratchet. Plug a new wiring harness onto the new controller.
Examine which wires from the old harness plug into which glow plugs in the cylinders. Pop one of the wires from the old harness off its plug, and push the matching wire on the new harness onto that plug. Repeat with each glow plug, until the old harness is removed and the new one is completely installed.
Reconnect the positive battery connection to the positive terminal on the car battery with the wrench, and then repeat with the negative connection.
