defenderdog
Active Member
Just to put my stamp on this. I have now worked out that my little amigos don't come on if I start the car with my foot on the brake pedal. I don't know if that signifies anything or whether I just need to get out more
Get out more often.
Sierraferry,
You mention that the alternator should take over the power once the car is running but interestinly enough. If I run the battery of a porsche down and then charge it up to full charge overnight, warning messages still come up to say that Porsche active suspension management is not working, rear spoiler is not working , traction control and abs are not working. These all start working after about 50 miles or so. I can only guess that these are complex systems that use up a lot of energy. Could this be the same for the discovery too? A good test is to see if the chap with the dodgy battery can correct his fault with a new battery.
Defenderdog - the world is round not flat. As Sierraferry said, anything is possible on these cars. He may not beleive it himself but hey if I am right, this will be the first time that it has been mentioned and may save a few hefty bills.
sierrafery
Well-Known Member
Yes, it seems very odd to me as i find no scientific explanation(for the time being), but i believe what you say so i'll think about that though it would be good to hook up a voltmeter somehow and watch the voltage when the symptom occurs and if it's steady around 14V it still remains the rectifier issue which unfortunately is not verifiable without oscilloscope, the battery acts as a kinda damper too on the alternator output so if it's interrupted or it's internal resistance fluctuates hard it can disturb the output... i've found myself this problem on a friend's D2 after the charging system passed a rudimentary check at a garage, the problem is explained here http://www.circuitspecialists.com/blog/testing-an-alternator-with-an-oscilloscope/ , so you'll see 14V output with voltmeter but if the waveform is like img 4 then it's not well rectified and it can hurt the battery and disturb various ECUs ... what ever it is it's the first time i see 3 amigos linked to a weak battery with engine running
sierrafery
Well-Known Member
it might be also due to SVS as the released pedal reading(3kohm) is out of the accepted range while the depressed pedal(1kohm) input is good and the system passes the self check only then
Just googled abs faults and weak battery. Seems there is a tie in on other vehicle types. A poor battery can result in am number of odd warning lights being tripped esp traction and abs. Thanks of taking an interest in this topic. There is a range rover chap who mentions a range of error lights which he was having a problem with. Tese all disappeared when he needed to change his battery in winter.
sierrafery
Well-Known Member
the newer LRs or other vehicles have a different kind of so called ''intelligent'' charging system which can detect if the battery is weak... not the case on a D2, IMO better make that SVS wiring mod and you'll be ok ... if the ABS light stays on alone after the TC and HDC are out but goes out too when the vehicle exceeds 10mph then it's a sensor signal related fault(which can be worn hub too), that's how you recognise a sensor related fault compared to SVS or others where all the 3 amigos reset at the same time
brian47
Well-Known Member
You're dealing with a Discovery 2 which whilst some people will tell you it's full of nasty electronics, in reality it's got more basic electrics rather than electronics. Mainly relays and diodes unless you get deep into some of the ECUs.
On more modern vehicles, I don't doubt that wierd voltages can upset all sorts of things but from what I've heard the only thing that low voltages will cause on a Disco is not starting.
Everyone is saying do the SVS mod, please don't google reasons not to. As I've said, it costs very little and if you do it and it's not required, there's no need to remove it. It won't have any detrimental effects at all.
On more modern vehicles, I don't doubt that wierd voltages can upset all sorts of things but from what I've heard the only thing that low voltages will cause on a Disco is not starting.
Everyone is saying do the SVS mod, please don't google reasons not to. As I've said, it costs very little and if you do it and it's not required, there's no need to remove it. It won't have any detrimental effects at all.
sierrafery
Well-Known Member
Just dont forget that while 3 amigos are on ABS, EBD or TC are at reduced performance or completely disabled depends on which default the system is so for your(or others) safety especially that winter is coming imo better fix that before anything else.
defenderdog
Active Member
Ah that makes good sense. Tried to remove the shuttle valve the other day but the Alan key bolts were bloody stiff as hell and I was running out of light so bolted block back in. But will have it out tomorrow and try again and test the valve on my meter.
Just reporting back. I have not has the 3 amigos back since the charge up. I am though aware that if I am correct in my case that it is the battery, then this underpowered battery will be an issue once the cold weather comes. Although the car starts no problems, the cold will put additional pressure on the battery and could start of the three amigos again. I'm not willing to risk this so just purchased a new battery 115amps and 1000 cca. I am hoping never to see the three amigos again.
sierrafery
Well-Known Member
if the test with the meter gives you good readings it means that the problem is in the internal contacts of the SVS assy(the big one) and the input doesnt reach the ECU... as it's explained in tha graphic i linked ..:defenderdog" said:Ah that makes good sense. Tried to remove the shuttle valve the other day but the Alan key bolts were bloody stiff as hell and I was running out of light so bolted block back in. But will have it out tomorrow and try again and test the valve on my meter.
OR!!! the N/C contact of the brake pedal switch is not closed and the ECU doesnt get the info that the pedal is released but it gets the 3kohm released pedal input... try to adjust the switch by fully depressing the pedal and pull out the switch's the plunger to maximum allowed ... the brake switch's inputs are readable with tester or if you have cruise controll see if it works and if it does the switch is OK
sierrafery
Well-Known Member
IMO you should find somebody with an oscilloscope to check the alternator output cos how ever i look to this there is a lack of logic to me:
1. if the battery is strong enough to start the engine after a charge after that it's under alternator supply while the engine is running so it's not supposed to loose power in the warm engine bay while driving(provided there's some issue with the charging).
2. if the battery is completely fubar'd it would not hold enough power to mstart the engine
3. even if the new strong battery will not make issues at the beginning if there's a alternator rectifier problem it will kill that new battery too in no time
so be aware
sierrafery
Well-Known Member
no, i doubt the garage will test your alternator with oscilloscope, dont you have an electronist friend who has one...he'll tell you if the waveform is suspect or not, worth a try, better rule this out 100% than ruin your shiny new battery
sierrafery
Well-Known Member
unfortunately not, only oscilloscope
brian47
Well-Known Member
For what it's worth, I reckon ldrego is seeing problems where none exist.
If the battery holds enough charge to start the vehicle in the morning then it should be OK, but buy a new one if you want to.
If the alternator can supply 14 plus volts measured directly across the battery when the engine is running at about 1500 rpm, NOT tickover then that should be OK, but buy a new one if you want.
The 3 Amigos could well be a faulty hub or ABS sensor, but since the sensors are built into the front hubs and changing the hubs is the only sure fire way of clearing that fault (if one exists there) then buy one or two if you want.
So far we've suggested that you do the SVS mod, but you want to hold off on that until next spring but until it's done and that fairly common source of the 3 Amigos can be ruled out, everything else is just guesswork and shootin' in the dark.
The mod takes about two hours at the most, you can do it while you're waiting for the latest coat of rust proofing to dry.
If the battery holds enough charge to start the vehicle in the morning then it should be OK, but buy a new one if you want to.
If the alternator can supply 14 plus volts measured directly across the battery when the engine is running at about 1500 rpm, NOT tickover then that should be OK, but buy a new one if you want.
The 3 Amigos could well be a faulty hub or ABS sensor, but since the sensors are built into the front hubs and changing the hubs is the only sure fire way of clearing that fault (if one exists there) then buy one or two if you want.
So far we've suggested that you do the SVS mod, but you want to hold off on that until next spring but until it's done and that fairly common source of the 3 Amigos can be ruled out, everything else is just guesswork and shootin' in the dark.
The mod takes about two hours at the most, you can do it while you're waiting for the latest coat of rust proofing to dry.
Ok it's been about 10 days or so with no abs faults and today one abs fault. life sucks. It looks as if the shuttle valve is at fault so this will get a going over on Friday. Once again. Thanks to all the guys who took time to comment .
Is like to say that this car really is brilliant as it pushes my mind a lot, sometimes in the wrong direction but hey, it's always working.
Will let you know if the shuttle valve sorts it out.
Is like to say that this car really is brilliant as it pushes my mind a lot, sometimes in the wrong direction but hey, it's always working.
Will let you know if the shuttle valve sorts it out.
