VW T4 Forum - VW T5 Forum banner
1 - 13 of 13 Posts

·
Registered
Joined
·
114 Posts
Discussion Starter · #1 ·
Hello all I seem to have battery drain, checked the battery and alternator, battery producing 12.8 v and alternator producing 14.7v even under heavy load so about where they need to be.
Van was as flat as a daisy the other day once bump started it was fine all day, started it this morning slow to turn over but started, its a 2.5 ex AA I tried checking the drain using a multi meter but for what ever reason if you disconnect the battery negitive and use the multi meter to make the contact between the battery and the lead it isn't registering any voltage even if the door is opened?
Checked with a 2nd meter just in case but no joy.
Has anybody any ideas? is there anything built into aa vans that will prevent this check being carried out.
Many thanks Mark.
 

·
Registered
Joined
·
1,186 Posts
Typical problem on these vans is the coolant run on pump staying on permanently. It is a little motor which is part of the coolant system and it prevents hot areas forming in the engine after it is shut down by continuing to circulate the coolant until it drops below a certain temperature. The thermostat switch which controls it is known to fail, and the pump then runs constantly. Stick your head in the engine bay when the engine is off and listen for a whirring sound.
The pump can be found below the radiator, attached to the forward cross member.
The thermo switch for the 2.5 which controls the pump is the lower of the two which fits into the 't' flange on the engine block. It can be found by looking above the alternator. It is a tight squeeze in there, so belly pan off and looking up is a better option. The thermostat is a 4 pin type, as it contains the switch for the run on pump and a sensor for the temp gauge.

The reason nothing operates when you remove the battery negative and put the multimeter in to measure voltage, is because on voltage setting, the multimeter does not complete a circuit. You need to switch the multimeter to measure current, this usually involves plugging the test leads in to the other holes on the multimeter body and rotating the front dial to an appropriate DC current setting.
Remember: Voltage can be measured without breaking a circuit, as it just measures the difference between the state of charge of two points.
To measure current you have to break the circuit and re join it with the multimeter in line, as it is measuring the rate of flow of charge through the circuit, and therefor this charge must flow through the multimeter.
If you disconnect a terminal of your battery and then add the multimeter in the gap when it is set to measure voltage, it will read zero, because the difference in charge between the two points will be zero. Doing this is just like putting both probes of the meter on the same terminal of the battery.
 

·
Registered
Joined
·
1,188 Posts
it mite be just down to the battery being old and the cold weather mines the same on the od day it will be flat starts and runs all day in the mornings slow turn over
 

·
Registered
Joined
·
1,186 Posts
Crewes, have you checked your coolant run on pump? It will give these symptoms, and is easy to miss. Just a thought. My pump is currently unplugged while i find the time to change the thermo switch (not done it yet as it results in coolant loss and i can live without the pump for a few months)
 

·
Registered
Joined
·
114 Posts
Discussion Starter · #5 ·
Thanks Lads I will get back to you, I can see where I went qrong with the multi meter It was set to measure dc 10v but I disconected the battery then tried to measure as apposed to connecting the meter then taking the lead off.
If I get chance I will have a go today thanks.
 

·
Registered
Joined
·
587 Posts
I had the same problem with my T5 recently. RAC guy tested both alternator and battery and pronounced them fine. Could not find any drain with meter when fuses were pulled so eventually decided to get a new alternator fitted. Garage said that the battery was also gubbed . Both renewed and problem solved! ( Bigger battery fitted this time ) £295.00 for job and well worth it.

Cheers, J
 

·
Registered
Joined
·
10,601 Posts
Breakdown firms are not good at diagnosing these faults, especially the RAC. Good for a tow and that's about it.
 

·
Registered
Joined
·
674 Posts
I Had this problem for two months, just thought the battery was dying in the morning , it turned out to be a lazy starter motor, it just started going slower and slower till eventually just a click from solenoid, as if the battery was flat.

changed it after talking to a guy on here, and its been fine ever since, so check your starter

Alan
SB
 

·
Registered
Joined
·
4 Posts
Hi,
I have had a Battery Drain issue appear for the last few days (T4 1994). The battery was draining from fully charged to nothing within 30 mins.

After changing the battery - not necessary, I discovered it was the Glowplug Relay on the Fuse Board. I did this by checking each fuse with a Multimeter and having got to the end of the fuses, I started puling all the relays just above the fuses, just in case. When I pulled the Glowplug relay all was suddenly better.

I hope this helps someone in the future.
 

·
Registered
Joined
·
567 Posts
I've had this a few times over the years, the jump start on your flat battery may have killed your alternator so that even though it charges the battery while engine is running overnight the battery will drain back through the damaged alternator. :(
 

·
Registered
Joined
·
532 Posts
Im with Squarebanana on this one

Mine did exactly this until i did a starter strip, clean & fitted new Brush plate.

starts on the button and no battery drain now. previously replaced battery to no avail.

Mike
 
1 - 13 of 13 Posts
Top