guineafowl21 said:
Voltage drop is caused by current flow through a resistance. @Alibro, your battery voltage should not drop that low with the ignition in position II - this is the first problem to be isolated.

If it's glow plugs, the relay will click off after a few seconds. If not, pull and replace fuses and relays until the voltage climbs back up - having first noted your radio security code. You will hopefully find the circuit responsible and can then pursue that avenue.

If no joy, I strongly suggest a voltage drop check along the main battery cables. Load the system by turning on the headlights and measure the voltage between engine block and battery negative. Measure the voltage as well between battery positive and everywhere the heavy positive cable goes - starter post, fusebox busbar etc.

You have to locate that voltage drop. Although your bypass switch logically suggests the relay or its feed, this might be a red herring - I had an internally corroded earth strap on ours that caused many problems like yours, but was dropping several volts just with the headlights on and causing the various ECUs to shut down upon cranking. I didn't measure the feed to the starter relay but I guess it would have been disappearing.
Click to expand...
I was surprised myself to see such a voltage drop but was assuming heater plugs, I figured maybe one had gone low resistance and was drawing too much current. I guess your right that I should be looking elsewhere too so I'll take a look later to see what fuse feeds the heater plugs and start there.
 
To help you on your way -

IMG_0322.PNG
 
If it is the glow plugs causing the volt drop it should go away with a warm engine. A dodgy battery cell, weak or sulphated battery will show the same symptoms. A shunt test will show up a duff or failing battery
 
wammers said:
If it is the glow plugs causing the volt drop it should go away with a warm engine. A dodgy battery cell, weak or sulphated battery will show the same symptoms. A shunt test will show up a duff or failing battery
Click to expand...

The problem never happens for me when the engine is warm and the voltage drop was still too high with a new battery.
 
Alibro said:
The problem never happens for me when the engine is warm and the voltage drop was still too high with a new battery.
Click to expand...

Glow plugs will always cause a voltage drop, maybe look at them. It is how fast the battery recovers from that load that indicates it's condition. Just like a shunt test. Trying to turn the engine over with glows still active with a duff battery is always going to cause a problem.
 
I'd expect to see a degree of volts drop across the battery, with the engine not running. The electrical loads imposed by all the active systems are quite high. I've measured 25 Amps being drawn after the glow plugs have shut down. The glow plugs will draw 40 to 50 Amps for a few seconds too. This would be on top of the 25 A running current normally seen. Running a current like this from the battery, will drop the terminal voltage.;)
 
andyfreelandy said:
Thanks LUKBENPHI - the more feedback like this, the more it just proves that it is NOT a failure of any connection or battery, it is 'the way the car is'.
Click to expand...

No probs, if it also helps I never saw the glow plug light illuminate on my td4 at all hot or cold in the time I owned it so not even sure any of them were working.so the volt drop i swa on mulitimeter cant be atributed to that i dont think

Needed a reliable car for 80 mile daily commute so it went quiet sharpish when realised it was playing silly buggers after I'd changed the fuel rail sensor harness

Nodge68 said:
The immobiliser is pretty easy to prove. The starter switch feeds 12 V crank signal to pin 8 of immobiliser ECU on the White/Red (WR). If the transponder says OK the IM ECU sends 12V down pin 7 on the Red/White (RW) to the starter relay.
So linking these two out at the IM should allow the starter to crank. This will prove the relay in the immobiliser is working or not.
Click to expand...

think i follow you :confused: mine cranked just would start so suspect im was ok on mine
 
Yes they each contain matching codes that need to be passed between them to mobilise the car. That's why when you need to replace the engine ECU you need to get the matching CCU as well. That means you need the fobs....
 
andyfreelandy said:
This is interesting - looks like as well as disabling the start relay the Immob ECU needs to send a code to the engine ECU to start !
http://www.gomog.com/allmorgan/LandRoverSecurityManual.pdf

Why do we make these things so complicated ! What was wrong with a door switch connected to the horn like my 100E had??
Click to expand...
That doesn't comply to the theft prevention standards.
Just link out the starter connections at the immobiliser, as previously posted;)
 
Tonight I was working at my 2nd Freelander again as I wasn't happy the glow plugs were working. I tried metering them and they seemed to be open circuit so I fitted the new ones (which metered out at 1ohm) and rechecked the voltages again.
The voltage drop was a bit more this time but still less than the other car.

Ignition off
20161207_203021_zpsoiqnggqw.jpg


Ignition on to position II

20161207_203035_zpsewy7qbnf.jpg


When the heater light on the dash went off the voltage came back up to 11.3V or so. I haven't had a chance to check what is pulling down the voltage on the other car yet but hopefully will next week. I have diff supports to repair on Bertie when the Poly bushes arrive.
 
Alibro said:
Tonight I was working at my 2nd Freelander again as I wasn't happy the glow plugs were working. I tried metering them and they seemed to be open circuit so I fitted the new ones (which metered out at 1ohm) and rechecked the voltages again.
The voltage drop was a bit more this time but still less than the other car.

Ignition off
20161207_203021_zpsoiqnggqw.jpg


Ignition on to position II

20161207_203035_zpsewy7qbnf.jpg


When the heater light on the dash went off the voltage came back up to 11.3V or so. I haven't had a chance to check what is pulling down the voltage on the other car yet but hopefully will next week. I have diff supports to repair on Bertie when the Poly bushes arrive.
Click to expand...

Hi Ali. I think you'll find that the glow plugs will continue to draw some power, after the light has gone out. I've not checked on the TD4, but most other diesels do. So might be worth checking the voltage at the glow plugs to see exactly how much voltage is fed to them and when. 1 Ohm for new plugs is spot on;)
 
Nodge is right - I had cold starting problems a while back and connected a voltmeter across the glows and had it in the cab. Sometimes the glows stay on a while after the light, sometimes the light doesn't come on and the glows power after engine fires. I can only assume that the Engine management provides what it thinks is the optimum 'glow time' for best emissions. I think the light is an indicator of when to turn the key to start, perhaps too hot is as bad as no glow???

I would be very surprised if all 4 of your old glows were open circuit - test them out of the car to confirm not bad connection of your meter??.
 
Haven't had time to read the thread, so excuse me if I'm piffing in the wind.
Are you aware if the one with the voltage drop has a FBH or PTC heater. Mine has the PTC and when the ignition is set to 2 and the heater dial is past 1o'clock the voltage drops due to the electronic PTC kicking in.
Just a thought.

Mike
 
Skinny Mike said:
Haven't had time to read the thread, so excuse me if I'm piffing in the wind.
Are you aware if the one with the voltage drop has a FBH or PTC heater. Mine has the PTC and when the ignition is set to 2 and the heater dial is past 1o'clock the voltage drops due to the electronic PTC kicking in.
Just a thought.

Mike
Click to expand...

The PTC heater is wired through the oil pressure switch, like the HFW. This stops working unless the engine is running;)
 
Skinny Mike said:
Haven't had time to read the thread, so excuse me if I'm piffing in the wind.
Are you aware if the one with the voltage drop has a FBH or PTC heater. Mine has the PTC and when the ignition is set to 2 and the heater dial is past 1o'clock the voltage drops due to the electronic PTC kicking in.
Just a thought.

Mike
Click to expand...
I'm not sure if it has either but it has a higher spec than Bertie the fire engine so might have a FBH.
It has been starting OK since I replaced the battery but the weather has been warmer and as already said that is probably only a temporary solution.
 
Ali. The TD4 had the FBH regardless of spec. The engine is very thermally efficient. In the winter, there's little waste heat to warm the cabin. So LR fitted the FBH to boost heater performance in cold weather.
Of course it aslo has the ability to preheat the engine before starting a journey, if it's activated by a remote or timer;)
 
Last edited:
Nodge - early Td4 all had the FBH as standard then for 2002MY the PTC heater was introduced to replace the FBH as standard and FBH was an option and standard on some higher specs

This strategy was continued until run out
 
td4van said:
Nodge - early Td4 all had the FBH as standard then for 2002MY the PTC heater was introduced to replace the FBH as standard and FBH was an option and standard on some higher specs

This strategy was continued until run out
Click to expand...
I don't know what Bertie has but I couldn't see any sign of an exhaust under the wheel arch, the heater works great though.
 
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