Could be bad glow plugs.
Starter Relay Isuzu Trooper (Diesel Engine) located in fuse box (engine room), grey color. They have 4 relay (Power Windows-black, AC-black, Engine/Alternator-blue, and Starter-diesel engine-grey)
Check wiring at starter Check battery cables for looseness or corrosion "Rap" starter with a hammer to see if brushes are stuck and need replacing Engine seized?
A single click and no response from the starter usually indicates a faulty starter relay/solenoid switch. It could also be a loose connection on the battery cable.
Bottom left of engine
The starter relay on most Toyota Forerunners is located on the right side of the engine, in a fuse box in the engine compartment. However, on models with the 2UZ-FE engine, the starter relay is located on top of the engine.
On a 1990 Chrysler New Yorker, the starter relay is built into the starter. The starter is located on the front of the engine, behind the engine mount.
starter, starter relay, battery, high resistance in batter/starter cabels just a few things that will cause this.
The starter relay on a 1992 Pathfinder is mounted between the transmission and engine block. The starter uses a gear drive to crank the engine and help it start.
The 1996 Dodge Dakota starter relay switch can be found on the firewall in the engine compartment. The starter relay switch will be on the drivers side of the firewall.
The starter solenoid/relay switch is going bad. Eventually, it will just click and not start.
The starter relay on a 1999 GMC Suburban with the bib block engine is located on the solenoid for the starter. The solenoid for the starter is on top of the starter.
I believe yours has a starter mounted solenoid and not a relay.