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Discussion Starter #1
Hi,
Have been troubleshooting a voltage issue, I changed both positive and negative cables and now get less than 100mv resistance throughout.
The voltage is still low 14.10v max @2000rpm, though when I clip my multi meter ground wire to the radiator (positive wire on positive battery terminal or Alternator output terminal) I measure 14.4 volts.
The ground cable to ground battery terminal is new and clean. Battery is new. Where else should I check?
Thanks
 

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Discussion Starter #2
Failed to mention this is a 2004 Range Rover (M62 BMW engine). I'll search for other grounding straps today. Asking for specific locations. Tks
 

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2002-2005 Range Rover MkIII / L322
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I am not sure what problem you are having that you are worried about the .3V?

Remember that there are no perfectly conducting wires, so there is always a drop when you measure voltage at the load end vs. the battery end. With the engine running, you should see about 14.4 across the battery terminals. The RR actually increases idle RPM to maintain this voltage. So, your system should be supplying the 14.4v, and it sounds like it is if you can get the 14.4v acrosss ANY location. As to the 14.1v...where are you measuring that? Remember if it is at any accessory location that it will always be less than the 14.4v

If you are having issues with some components that is related to voltage, then look at that particular component's.connections. But, offhand 14.1v sounds great to me. When you start getting less than 13v at an accessory, then I would think there is a connection problem.

Also, the radiator is rubber mounted, with rubber hoses...so on many cars it is electrically inert. A large bolt on the engine or frame is a better location to ground your test lead.
 

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Discussion Starter #4
Thanks for your response. Yes, I am concerned about the .3v since the electrical sticky states the voltage MUST be 14.2v to 14.4v and I'm not seeing it anywhere other than the radiator. Wherever else I test, such as battery terminal to terminal, Alternator to Alternator body is 14.0 to 14.1 @ 2000rpm. etc.
The problems I'm experiencing after approx 30 minutes of driving: DSC inactive, Trans Fail Program, ABS failure, brake light on etc. After clearing all with Allcomms kit, its good for another 30 minutes. I've upgraded all main Pos & Neg cables I can lay my eyes on to a 1/0 size with only .70mv resistance throughout. After this upgrade I thought I'd cracked it since the voltage did increase from a max of 13.5v to 14.0v/14.1v but these errors keep returning.
My next test is to run another negative cable directly from battery to block. If I can increase the voltage to that recommended on the Electrical sticky, I have at least a chance of fixing other failing components, if any, but not until I get the 14.2v to 14.4v.
Once again, thanks for pitching in!
PS: New Battery, New cables, Tested new Alternator without change.
 

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Discussion Starter #5
Thanks for your response. Yes, I am concerned about the .3v since the electrical sticky states the voltage MUST be 14.2v to 14.4v and I'm not seeing it anywhere other than the radiator. Wherever else I test, such as battery terminal to terminal, Alternator to Alternator body is 14.0 to 14.1 @ 2000rpm. etc.
The problems I'm experiencing after approx 30 minutes of driving: DSC inactive, Trans Fail Program, ABS failure, brake light on etc. After clearing all with Allcomms kit, its good for another 30 minutes. I've upgraded all main Pos & Neg cables I can lay my eyes on to a 1/0 size with only .70mv resistance throughout. After this upgrade I thought I'd cracked it since the voltage did increase from a max of 13.5v to 14.0v/14.1v but these errors keep returning.
My next test is to run another negative cable directly from battery to block. If I can increase the voltage to that recommended on the Electrical sticky, I have at least a chance of fixing other failing components, if any, but not until I get the 14.2v to 14.4v.
Once again, thanks for pitching in!
PS: New Battery, New cables, Tested new Alternator without change.
Re: .70mv should read .07mv
 

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2002-2005 Range Rover MkIII / L322
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How old is your battery? I have had those symptoms 3 times, and every time changing the battery solved it.

If you follow my logic...if you are getting 14.4v anywhere, then the alternator must be putting that amount out, since it is the only part that MAKES more voltage than the battery in the system. So, if the alt is good, but the battery posts do not show the 14.4, then the battery must be pulling too much amperage.

Also be aware that most voltmeters are not all that accurate. You can also try a different meter to see what you get.
 

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Discussion Starter #7
Hi,
CJD and everyone else thanks for your input, the battery is new. I did look at my Multi-meter and it read under actual voltage by .1v.
I rigged up the new earth/ground 1/0 cabling directly to the block and together with new 1/0 positive I managed to increase overall voltage to 14.2v and since then ZERO errors. Still early days so only time and mileage will tell and I'll report if any other issues.
 
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