Unable to start 1hd-t without battery booster

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R

Ragonz

Joined
Apr 13, 2024
Threads
4
Messages
16
Location
England
Reposted from the 80 series forum as they said the diesel area would be better.

Hello everyone, I've been searching all over for the past couple days to try and make sense of all the various bits of information on this site and others but I'm struggling.

My 1hd-t 93 80 series will not start unless I put a battery booster on the driver side (left whilst looking towards the front of the car as its a UK spec) This leads me to suspect that there is somthing preventing the other battery being used when starting.

I don't believe the issue is the starter as it would not start at all if this was the case
I have tested both batteries and they are both good
I have replaced the fusible link on ther right hand side battery (passenger side) as I thought it may have been this.
I will be testing the cylindrical voltage converter unit later today as I found the guide on how to do so via the 80 forum.

Could anyone point me in the direction of a couple bits of information
How to test any relays involved in the process

How to identify which one of the FSM's in the resources area is applicable to me as there are quite a few.

Aplologies if I've overlooked places where the above is answered.
 
Hi R. You have not mentioned whether it is cranking slowly, or if it is not starting when cranking normally.
 
John Young said:
Hi R. You have not mentioned whether it is cranking slowly, or if it is not starting when cranking normally.
Click to expand...
Without battery booster it either cranks very very slowly for a brief moment or just clicks at me

With battery booster on the driver side (left as you look at the vehicle) it cranks and starts immediatly
 
I'm sure you already are thinking this, but it sounds to me like the relay to provide the 24v in series for the starter is not functioning. If memory serves, It is located in the engine bay on the left-hand side (which is the passenger side on your RHD HDJ81). Look right next to the left-hand battery; the relay is bolted directly to the inner fender guard, just behind (aft of) or tucked slightly underneath the left battery tray. I would check whether it is functioning.

Also you have not said what voltage is present at the starter during starting. This also could just be a faulty starter.

And have you taken out the 2nd battery and confirmed that it can provide full current?
 
Did you check all the terminals? Essentially all the thick cables, from both batteries to the series parallel relay (as John says, it's a cup sized cylinder, both batteries are connected to it, it powers the starter by terminal 30), all the ground points too. If there's a loose or corroded connection anywhere, this could be the symptom too.

The relay can be checked this way according FSM, but FSM specifically says slow crank is either battery charge low, battery cables loose, corroded or worn or starter faulty. From RM172E engine repair manual. Did you check the batteries while they were disconnected?

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Is your starter 12v or 24v?
 
I'm sure that you did this already but I've seen it overlooked many times. when you say you tested both batteries and they are good did you disconnect them from the truck before testing? Those are all good relay tests listed but even easier is to just check for 18v+ volts at the output (it's going to be lower then 24v with the starter engaged) I know your across the pond but if that relay ends up testing bad I have a good used one from a 12v start conversion.
 
When looking at the car from the front
Right hand side battery 13.22v
Left hand side (driver side) battery 12.94v
Both tested out of the car

The tests on the voltage converter all beep / don't beep as expected

Starter is a 24v one

The tests on the starter relay however do not, no beep on first test without battery
But also no beep with battery connected (you can hear the relay clicking when 12v is applied)

Screenshot_20260314_165709_Chrome.webp


Screenshot_20260314_170028_Photo Editor.webp
 
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If the starter relay was faulty, you would have no crank at all, because the starter relay only engages the huge ,,relay'' in the starter itself, which then makes it crank. I.E. it would work 100% or not work at all, it can't halfway work. Your series parallel relay seems okay as well, your batteries seem fine, therefore I am still suspecting the wires themselves. I am also pretty sure it can be the starter itself, it's actually pretty easy job to take it out and check the graphite blocks and overall function out of the vehicle, if all else fails that is. If you connect it directly to a 24V battery (or two 12v connected in series) it should crank like crazy.

If it does, I am afraid you have to check how much voltage actually gets to your starter when you crank it. Get a friend or long wires to your voltmeter and see what goes to the main starter terminal (#30).

And actually if nothing works, I would strongly suggest going the 12V way. Buy a new starter for a 76 series, 11 teeth, go though this forum for the wiring clues. This will work 100%.. TBH the 80 series diesel starting is kinda black magic.

Oh and by the way; when I had my electrical headache 2 years back, I was actually able to crank the 24V starter from only one battery, using jump start cables. If the starter is okay, it is able to start the engine on 12V only, just a bit slower. It was the way I started my truck for about a month. Put the key to ON, take jump start cable from left battery directly to the #30 terminal (acting as the main starter power), start with the key, take the jump cable off, and off we go.
 
I do not believe it to be the starter as its less than a year old and it does start the car If I chuck a battery booster on the left battery (when looking from front of car)
The starter relay was tested as it describes in the fsm (ie out of the vehicle and manually applying 12v to the E and ST pins) but I got no continuity when doing the test.

There are other electrical gremlins with the car as well which may be related but I wanted to get the starting problem sorted first.
 
In that case check the voltage at the starter itself at the moment of crank. With booster without booster. There's GOT to be a difference..

EDIT; not sure if that helps but you can check the cranking voltage if you disconnect the fuel cut off solenoid from the pump. There's a small screw terminal, on the back side, towards the rear axle. Disconnected, the starter will crank without the engine starting..
 
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I'm with Itchy on this. It can be surprising how thick power cables that look outwardly fine are actually problematic. The truck is over 30 years old at this point and corrosion creeps.

If the starter is new, and the relay is functional, and the batteries are good, then there is not much left other than defective power cables. It would be very useful to have an actual voltage measurement at the starter during starting. It it does turn out to be 24 volts then an issue with the starter would seem very likely. I would bet you will see something substantially less than 24v.

And on batteries, did you check the amperage? A battery that shows 13.4v may still have internal issues that limit its current. Your local parts store likely has a battery tester that tests under load, not just static voltage.

The good news is that there is a limited universe of possibilities.

In my own case I could never get the series/parallel relay to funtion as it should. Ultimately I gave up and sold the HDJ81 (which had been converted from RHD to LHD (badly), and as for the engine, I switched to a 12v starter.
 
Ragonz said:
When looking at the car from the front
Right hand side battery 13.22v
Left hand side (driver side) battery 12.94v
Both tested out of the car

The tests on the voltage converter all beep / don't beep as expected

Starter is a 24v one

The tests on the starter relay however do not, no beep on first test without battery
But also no beep with battery connected (you can hear the relay clicking when 12v is applied)

View attachment 4102798

View attachment 4102800
Click to expand...
the battery voltage only tells you the state of charge, how many cold crank amps do you have?
 
Further testing with a decent multimeter gives me beeps (continuity) where it should be on each of the voltage converter and the starter relay and no beeps where there should not be any beeps, so if I've ruled out those 2 components what else can I test?

There is now no cranking at all and the battery booster on the driver (righ as you look at car from front) trick no longer works.
 
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voltage present at the main (large) starter post and voltage present at the small soliniod connector when the key is held in the start position.
 
TheBussman said:
voltage present at the main (large) starter post and voltage present at the small soliniod connector when the key is held in the start position.
Click to expand...
Are you saying you are getting ~24v at the starter when you are trying to start it? If so, then it must be your starter motor. Easy to take out, and strip it?
 
StuCruiser said:
Are you saying you are getting ~24v at the starter when you are trying to start it? If so, then it must be your starter motor. Easy to take out, and strip it?
Click to expand...
he was asking what to test next.
 
Ragonz said:
Further testing with a decent multimeter gives me beeps (continuity) where it should be on each of the voltage converter and the starter relay and no beeps where there should not be any beeps, so if I've ruled out those 2 components what else can I test?

There is now no cranking at all and the battery booster on the driver (righ as you look at car from front) trick no longer works.
Click to expand...
Did you figure this out?

You mentioned the starter is clicking? This is the tell tale.


A couple of things could be happening.

The starter motor solenoid is not getting enough current to hold it in the engaged position, or it iss damaged.

Things to check.
1, Bad battery. Not enough charge in one or both batteries. Test the battery voltage while under load, ie, read the voltage while cranking, or while you switch on Hi beam headlights. Voltage should not drop below 12volts at either battery.
If one battery has a bad cell, it can show 12 bolts, but when you or a load on it, you'll only see 10-11 volts, and low current discharge. Using a booster pack might just be enough to compensate for a bad cell.
One bad battery will quickly kill the 2nd battery. If one needs replacing, replace both with new batteries of the same specs, CCA etc

2, Bad wiring. A corroded battery clamp, loose ground, or corroded battery or starter motor cable will reduce current going to the starter. Thoroughly check all the heavy battery, starter,ground cables and connections

3. The starter solenoid terminals are worn out. The copper terminals inside the starter solenoid (on the starter motor) wear out and erode from electrical arcing when the electrical curcuit is made, or broken while starting. What happens when you turn the key, the solenoid gets a shot of electricity, it activates which is the 1st click, tunes low current passing through the solenoid coil, and it can't its position, it resets, 2nd click, you're still holding the key at start, solenoid gets another shot if electricity, it activates, repeat repeat repeat.

Contacts are very cheap, and fairly easy to replace. The 24 volt starters burn through contracts faster than 12volt starters.



Beyond that, a bad key switch, or bad ignition key circuit wiring could be an issue. But, my money is on point 3, or point 1.
 
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