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Why can't I jumpstart my '99 DII?

6K views 42 replies 8 participants last post by  tyl604 
#1 ·
The battery ran down and I jumped it last week; started OK and I drove it around for a while. Parked and tried it again; it started fine.

This week I put the jumpers on it again and it will absolutely not start, will not even turn over and the lights and horns flash for about a minute - then go off - then come back on again..

I have a battery on the way but why won't it jump start? Regular cars used to to this and it did so last week.

Puzzled.
 
#29 ·
Reread my old posts and saw the comment about locking/unlocking twice; it worked the last time after I installed the new battery (three months ago). But did not work this time. Funny. It is as if the battery is disconnected. No headlight, no interior light. It seems that even with a very low battery the headlights should come on. Not today. Going to hook up the jumpers again and have wife hold the Mercedes at high rpm and see if it will jump. Maybe there was just not enough juice going through the cables at idle speed yesterday. Wish me luck.
 
#30 ·
That battery is completely dead so better not try to jump it cos it can have short between cells and it will ruin the donor's alternator. Send it back if it's in warranty and ask for other modell cos it seems that this one is sh*t or you have some major parasitic drain which can be caused by faulty alternator so that's why your battery died. Read the owner's handbook about the emergency starting procedure and warnings cos if you dont comply exactly you can ruin the BCU or IDM, happened to others
 
#31 ·
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Yep, it was the battery. Took it to Pep Boys and it checked out dead. They gave me a new one as the other one lasted three months. Installed and all is good. Agree - I will pull out my paper manual and read the emergency starting procedure anew.

I love this Land Rover - today.
 
#32 ·
OK, did you check te charging? cos if it's something wrong with the alternator this battery might be dead in no time as well
 
#33 · (Edited)
Correcto. My OBDII reader reports that; will take a look. Seems like it supposed to be charging at 13.5 or 14.5 or close to that? Maybe I should do it with the AC running to put a load on it?

It has:

vehicle speed
engine speed
water temperature
battery voltage
instantaneous fuel consumption
average fuel consumption
mileage measurement
shift reminding
fatigue driving reminding
low voltage alarm
high temperature alarm
speed alarm
engine fault alarm
fault code elimination
free switching between kilometer and mile
 
#34 · (Edited)
Yes switch on all the loads but that's just part of the test. The new battery should show 12.6+V after you switched off the ignition then after a night rest it should not be less than 12.5V cos if it is means there is an excessive quiescent current draw which in many cases is caused by the alternator itself. It can give normal charge but if one diode is shot in the rectifier there is a drain through it while the charging voltage is still good. This is more complicated than it appears and it can be diagnosed only with oscilloscope which too few services are doing: Alternator Troubleshooting with an Oscilloscope

normally it's good to measure the drain to make sure everything is OK otherwise it will keep killing batteries. The easy way is to measure the voltage on the battery after it stood over night and if it's not below 12.5V you should be OK.
 
#36 ·
Those voltages i said were about the battery without ignition on before you crank it so you need a multimeter for that
 
#38 ·
it's logical: 20V DC(or somethig which includes 12VDC if the scale is different)
 
#42 ·
FWIW it's with direct current voltage, the black must go to ground and the red to +
VAC alternates polarity 60 times per second (in USA) so it doesn't care, but VDC is directional
 
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