Generator Field Circut High

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SK2000

Member
Posts
37
Location
Northumberland
Hi Any really good techies our their that can assist.please.RR L322 2006 Jaguar engine
I have an error Generator Field Circuit High and have recently changed the Alternator as was advised was the likely cause. Battery light on dash still on and loud cooler fan starts up, revs rise to around 1100rpm. Now sounds like a bus and feels likes it’s in a go slow mode.The battery initially wasn’t charging but new alternator and replacement faulty wing mirror with open circuit fault seems to have rectified battery voltage which is sitting at 12.2v. No other error codes in gap idtool.Anybody with specialised knowledge can assist me with where I could look at next or lead me through wiring checks. Any help would be appreciated.
 
Battery voltage should be minimum 12.6 volts static just after switching off and over 14 volts charge when engine is running just after start. If you don't know what you are doing, take it to someone who does.
 
As Wammers said you should have at least 12.6 volts after just switching off or nearer 12.8 volts, 12.2 is nigh on a flat battery. At 2K rpm ,the voltage across the battery should be in excess of 14.8 volts and could be up to 15.5 volts on you year of car.
Could be you battery is fecked.
 
SK2000 said:
Thanks Datatek, when car is running battery is at 13.7v. Range Rover say that is where it should be. I’ll do a search on the forum.Cheers
Click to expand...
No need to search the forum, the values given by @wammers and @Datatek are not only correct but given by knowledgeable members. You wont get any different values, unless of course its someone posting about a fault :rolleyes:

P.s it won't be the first time Range Rover are wrong ;)
 
Hi I’m not searching the forum for what the voltage should be I’m just trying to find anyone who can shed light on the procedures for testing the field circuit on the L322 beyond my knowledge. Testing the alternator duty cycle 0% and the Alternator circuit short to voltage is 12v. Checked the terminals and they appear okay. I’m then out of ideas other than a PCM update which is available but another £120 from independent RR. Got checked by local garage and no help. About £450 down with replacing parts and nothing todate.
 
SK2000 said:
Hi I’m not searching the forum for what the voltage should be I’m just trying to find anyone who can shed light on the procedures for testing the field circuit on the L322 beyond my knowledge. Testing the alternator duty cycle 0% and the Alternator circuit short to voltage is 12v. Checked the terminals and they appear okay. I’m then out of ideas other than a PCM update which is available but another £120 from independent RR. Got checked by local garage and no help. About £450 down with replacing parts and nothing todate.
Click to expand...

I'd take #2 into consideration and find yourself a local LR, independent, with a good knowledge of the model. There are very knowledgeable people on here but sometimes , without offence, ability has to match given information. From Wammers' post I can only think this is one of those times.
One our other gurus may have a different idea.
 
SK2000 said:
Hi I’m not searching the forum for what the voltage should be I’m just trying to find anyone who can shed light on the procedures for testing the field circuit on the L322 beyond my knowledge. Testing the alternator duty cycle 0% and the Alternator circuit short to voltage is 12v. Checked the terminals and they appear okay. I’m then out of ideas other than a PCM update which is available but another £120 from independent RR. Got checked by local garage and no help. About £450 down with replacing parts and nothing todate.
Click to expand...
If the battery is fecked you may get the problems you have. Check the battery voltage a couple of hours after you have switched off.
A faulty battery can drag the alternator output down from the 14.8 + you should see to the 13.7 you have, the regulator will push the field voltage up to try to get the alternator output up to where it should be, thus your error message.
 
Battery was replaced with Varta and already checked and found to be okay but I reverted back to new R/R battery. Can’t be two faulty batteries. I’ve booked vehicle in to RR independent garage to hopefully deal. Thanks for your help...
 
Last edited:
SK2000 said:
Battery was replaced with Varta and already checked and found to be okay but I reverted back to new R/R battery. Can’t be two faulty batteries.
Click to expand...
Could be, I have had 2 new Varta batteries in the last 18 months that were not good. Other possibilities are high resistance connections, in particular check the earth bonding strap from the engine to the chassis. I've just re-read your original post, I see the battery warning light is staying on, so if like the P38 the D+ output of the alternator goes via the body control ECU, a bad connection anywhere on the line will also cause your problem as would a fault in the BCU. You really need specific diagnostics to look at the BCU and see what is going on.
 
SK2000 said:
Battery was replaced with Varta and already checked and found to be okay but I reverted back to new R/R battery. Can’t be two faulty batteries.
Click to expand...

Each cell is 2.1 volts it has six cells 6 x 2.1 is 12.6. That is the minimum for a charged battery. As Keith says minimum charge rate for your car should be in the 14.8 to 15.5 range. Dependent on alternator used and voltage control applicable to that unit. 13.7 volt charge rate is far to low for your year of car. If your car has a calcium battery 13.7 will never charge it fully and will cause it to sulphate up reducing it's capacity. You need at the very least 14.5 volts charge rate even for a calcium antimony battery. Full calcium needs a minimum 15 volts charge rate or more.
 
Thanks.. I was having a lot of problems with the hevac and then the heater /open circuit on the wing mirror which contributed to fecking the Varta. Replaced the FSR and the Hevac module and back to RR battery. Wing mirror changed yesterday and cleared faults to only leave P0626. I can only have them check this battery incase this one has gone the same way. It holds a voltage off the vehicle at 12.6v
 
SK2000 said:
Thanks.. I was having a lot of problems with the hevac and then the heater /open circuit on the wing mirror which contributed to fecking the Varta. Replaced the FSR and the Hevac module and back to RR battery. Wing mirror changed yesterday and cleared faults to only leave P0626. I can only have them check this battery incase this one has gone the same way. It holds a voltage off the vehicle at 12.6v
Click to expand...
The battery light staying on suggests it is not the battery.
 
SK2000 said:
Thanks.. I was having a lot of problems with the hevac and then the heater /open circuit on the wing mirror which contributed to fecking the Varta. Replaced the FSR and the Hevac module and back to RR battery. Wing mirror changed yesterday and cleared faults to only leave P0626. I can only have them check this battery incase this one has gone the same way. It holds a voltage off the vehicle at 12.6v
Click to expand...

The field windings have to be excited in order for the alternator to work. They are fed from the battery + via the BECM on ignition, charge lamp will illuminate. When the alternator starts to generate power the feed from the BECMs polarity is reversed and this extinguishes the charge lamp. Keith maybe able to explain it better than i can he is a leccy man.
 
Re these checks in the bcu or any system checks are any checks able to be carried out on the gap idtool live data. Battery checks are in the green on the gap idtool.
 
wammers said:
The field windings have to be excited in order for the alternator to work. They are fed from the battery + via the BECM on ignition, charge lamp will illuminate. When the alternator starts to generate power the feed from the BECMs polarity is reversed and this extinguishes the charge lamp. Keith maybe able to explain it better than i can he is a leccy man.
Click to expand...
wammers said:
The field windings have to be excited in order for the alternator to work. They are fed from the battery + via the BECM on ignition, charge lamp will illuminate. When the alternator starts to generate power the feed from the BECMs polarity is reversed and this extinguishes the charge lamp. Keith maybe able to explain it better than i can he is a leccy man.
Click to expand...
It's an L322 Tony, you are right, but it's a bit more complicated because I think that year of car has a smart regulator with different charge rates. Also, the BCU is not the same as the P38 BECM but the principle will be the same.
 
SK2000 said:
Re these checks in the bcu or any system checks are any checks able to be carried out on the gap idtool live data. Battery checks are in the green on the gap idtool.
Click to expand...
No idea about your idtool, so start with with the basics, check that the earth bond from chassis to engine is intact and the point where it attaches to the body is not corroded. When you have done that, run the engine at 2Krpm for a few minutes and check the voltage at the battery, it should be at least 14.5 volts. You say you have changed the alternator, I assume you fitted exactly the correct alternator? The alternator fitted to your car is, I think, different from run of the mill vehicle alternators.
 
SK2000 said:
Battery was replaced with Varta and already checked and found to be okay but I reverted back to new R/R battery. Can’t be two faulty batteries. I’ve booked vehicle in to RR independent garage to hopefully deal. Thanks for your help...
Click to expand...
Which trim is your vehicle and what size battery?
 
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