tonymaloney · May 6, 2025

My engine management light has just come on, amber. I have just run a code reader and it has come up with this little list! The cruise control is also not working and I have just noticed when reversing that it comes up with, "restricted performance" and then picks up.
I have erased all the codes and the engine management light has gone off. Could this be just one thing or do I need to be worried?
This is on a Discovery 4 2011.

Stanleysteamer · May 6, 2025

Welcome to the forum!

not an expert on the D4 but do know these vehicles are very sensitive to batteries that are not in tip top condition.
don't worry, more knowledgeable people like @gstuart will pop on soon to help you out.
By the way, what diagnostic is that? It may help us if we know.

gstuart · May 7, 2025

tonymaloney said:
My engine management light has just come on, amber. I have just run a code reader and it has come up with this little list! The cruise control is also not working and I have just noticed when reversing that it comes up with, "restricted performance" and then picks up.
I have erased all the codes and the engine management light has gone off. Could this be just one thing or do I need to be worried?
This is on a Discovery 4 2011.

Hi

Plus 1 what’s been mentioned about the battery from @Stanleysteamer, as if they get low can cause untold issues, , would u also let us know what software ur using plse

So indeed if all the codes have gone after clearing them, give it a short drive then rescan it to see if any come back as that will give u a better picture idea of actual current faults and not old ones

So will be a good idea to check the earth leads and clamps along with at the same time battery voltage with the engine off and then running to ensure there fully charged , don’t think u have a second aux battery fitted on ur early D4 , if the battery is older than 5 x years would be a good idea to fit a new one as that’s an average age on these vehicles as there very power hungry

If a new battery is fitted Plse ensure u reset the BMS module

Hope that helps

tonymaloney · May 7, 2025

Stanleysteamer said:
Welcome to the forum!

not an expert on the D4 but do know these vehicles are very sensitive to batteries that are not in tip top condition.
don't worry, more knowledgeable people like @gstuart will pop on soon to help you out.
By the way, what diagnostic is that? It may help us if we know.

It’s a Snap-on Triton D8 Model EEMS343

tonymaloney · May 7, 2025

gstuart said:
Hi

Plus 1 what’s been mentioned about the battery from @Stanleysteamer, as if they get low can cause untold issues, , would u also let us know what software ur using plse

So indeed if all the codes have gone after clearing them, give it a short drive then rescan it to see if any come back as that will give u a better picture idea of actual current faults and not old ones

So will be a good idea to check the earth leads and clamps along with at the same time battery voltage with the engine off and then running to ensure there fully charged , don’t think u have a second aux battery fitted on ur early D4 , if the battery is older than 5 x years would be a good idea to fit a new one as that’s an average age on these vehicles as there very power hungry

If a new battery is fitted Plse ensure u reset the BMS module

Hope that helps

The battery this morning before starting was reading 12.2v. When started was showing 14.5v. The battery has an indicator on it and that is green which means okay. Having said that when I retested the codes with ignition on within 10 minutes a warning error came up saying battery low start engine. All the codes came back again. I tried it without starting the engine and only one came back. See attached picture. U2005-85 vehicle speed signal above allowable range. @gstuart and @Stanleysteamer

Stanleysteamer · May 7, 2025

tonymaloney said:
The battery this morning before starting was reading 12.2v. When started was showing 14.5v. The battery has an indicator on it and that is green which means okay. Having said that when I retested the codes with ignition on within 10 minutes a warning error came up saying battery low start engine. All the codes came back again. I tried it without starting the engine and only one came back. See attached picture. U2005-85 vehicle speed signal above allowable range. @gstuart and @Stanleysteamer

I expect @gstuart will agree with me when I say that 12.2 volts isn't enough. Normally needs to be 12.6.
But he has already talked about batt voltages and conditions.
14.5 shows the alternator is OK, I would think.
The green indicator is a very vague thing to go by, it is a bit of indication is all.
One thing you could do is jump another batt onto it and see if it behaves itself, if you have a spare batt kicking around or another car you can connect to it with jump leads.
Best of luck mate.

gstuart · May 7, 2025

Stanleysteamer said:
I expect @gstuart will agree with me when I say that 12.2 volts isn't enough. Normally needs to be 12.6.
But he has already talked about batt voltages and conditions.
14.5 shows the alternator is OK, I would think.
The green indicator is a very vague thing to go by, it is a bit of indication is all.
One thing you could do is jump another batt onto it and see if it behaves itself, if you have a spare batt kicking around or another car you can connect to it with jump leads.
Best of luck mate.

Indeed mate ur spot on , with that in mind talking about external sources I’ve always been curious if there’s a scenario of the agm on one vehicle, ie the D4 and. Lead acid battery on another vehicle if that would ever upset the BMS monitoring system on the D4

Also As the D3 charges higher than the D4 if it would lead to an agm getting damaged, don’t know enough in depth knowledge of batteries so always wondered about that

Yeh I know I need to get out more , lol

gstuart · May 7, 2025

tonymaloney said:
The battery this morning before starting was reading 12.2v. When started was showing 14.5v. The battery has an indicator on it and that is green which means okay. Having said that when I retested the codes with ignition on within 10 minutes a warning error came up saying battery low start engine. All the codes came back again. I tried it without starting the engine and only one came back. See attached picture. U2005-85 vehicle speed signal above allowable range. @gstuart and @Stanleysteamer

Plus 1 what @Stanleysteamer has said about the min vdc battery requirement with the engine off , always best to use a multimeter directly onto the battery itself as then ur have a decent reading

Another thing to look out for are deteriorating earth cables , there’s a large one behind the front wheel arch liner , drivers side , another one on the gearbox

Another good way to rule out bad earths is use a jumper cable from the battery earth post to a good earth connection on the engine , which can be found using a multimeter , might have to scrap off some paint to ensure a good contact

Hope this is useful to u

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