Unable to start 1hd-t without battery booster

[AirheadNut]

I don't remember what year the wiring changed, but on early HDJ81's there is a harness connector underneath the washer fluid tank on the LH side of the engine bay, spilled washer fluid gets into this plug and corrodes the terminals and wiring. The starter trigger wiring runs through this harness and can fail intermittently from this corrosion. It is possible that putting a booster on the battery increases the voltage just enough to overcome corrosion in the plug. There are several threads on here that show the issue and repairs to the harness.

 

[Vulkyn]

Had a very slow crankcase myself, I swapped the battery from 64 amp to 80 amp and what a difference that made.

Im running 12 volts since the engine is installed on my fj62.
The other factor that helped a lot with pump timing, now prerry much cranks in 1 or 2 engine cycles with out glow plugs. (Only use them when it's cold have them on a cut out relay for on / off when needed)

 

[Ragonz]

Been a while since I've been able to take another crack at this so going to put everything into this reply so nobody has to dig around.

1HD-t 80 series 1993 fails to start without battery jump pack - initial problem

After diagnosing it now will not start at all even with the battery jump pack

Tested starter relay - good
Tested voltage converter cylinder thing - good

Both batteries test good -
Right hand side (passenger when looking from front) = 793cca
Left (driver) = 870 cca
Right hand side battery 13.22v
Left hand side (driver side) battery 12.94v

Voltage measurements from the starter when cranking -
Key in, not turned - 12v
Key in, cranking - 6v
Key in, not turned, battery booster applied - 12.5v
Key in, cranking, battery booster applied - 23.1v

Now that I've managed to measure that I do notice the following.
When the battery booster is not applied, I get a whirring/slightly grinding noise, possibly the starter trying to do somthing but not being able to? - I also see the dashboard do weird things such as the speedo climb whilst they key is in the cranking position.
When the battery booster is applied, I get the clicks from the relays but absolutely nothing from the starter.

Is my next step to look at the NSS? and if so do anyone have a picture of exactly where it is? or is it to connect a battery directly to the starter and see what happens?

 

[Squash]

Been a while.
Climb under the unit and tap the main starter feed from battery with the solenoid.
Use a sout wire or two screwdrivers to fire up the starter being careful with the screwdrivers that you do not touch metal.
This tells you that it's not your batteries.
This is also a good time to check the solenoid wiring. Clean up old grease etc.
Maybe run an emergency start system.
I've put in a few using a momentary switch.
Lastly there is a fusible link from the battery to starter relay. This link may test with a light, but is to worn for proper power supply under starter engagement.