.........hi guys and gals,
i have a starting problem caused by a flat battery.
my truck would not turn over every morning and sometimes during the day, showing classic flat battery clicking sounds when the key was turned.
i had the battery and alternator checked out and an unservicable battery was the outcome, via one of those hand held do-hickeys that shows the condition of the alternator and battery.
i had this done at 3 locations to make sure, and all 3 came up with the same problem......dead battery.
i replaced the battery last night around 1600 hrs for the correct type for the vehicle at a cost of £85.00. went to work this morning and truck started fine. finished work this evening jumped in my truck and .................. flat battery [&:]. got her going, and went to an associate of mine, andy,for a pre-arranged appointment to have a tune up for my L.P.G. conversion kit.
now, he says the alternator/charging circuit is at fault and has seen this before on a blazer. the alternator is showing an output of 13.5 volts, and according to andy should show 14.1 volts, and the problem is not the alternator but in th ECU. apparantly the ECU tells the alternator when to charge the battery.and the previous blazer was cured by importing a replacement ECU.

can anyone please confirm this? or give more info on the problem.
someone must have had a similar experiance.

all help gratefully received,
mick.

 

Have you checked to see if you have a current draw that is pulling the battery down?

The alternator should be over 14V when charging properly. You could remove the alternator and have it tested independently at Autozone or Advanced.

 

thanks for the quick reply, no i havnt checked for a current draw, how would you do it? the draw would have to be fairly substantial to pull a big battery like this down in a short while.

the charge on the dash is only showing 13.5 volts at best, and is there any truth in the ECU thing?

mick.

 

At the very least, you will need a test light, but a good multimeter will show you more. To see if you have a current draw, you need to remove either the positive or negative battery cable. With the multimeter set to the highest AMP setting, put it in line with the battery cable, making the connection. The draw should not exceed .035A (35mA) after 10 minutes of reconnecting the terminals with the multimeter in the loop.

If you experience a draw greater than the amount specified, then you need to determine what circuit it is coming from. To do this, reconnect the battery cable which was previously disconnected and remove the fuses one at a time, probing across the fuse terminals, monitoring the AMP draw.

The ECU does control the alternator to a certain extent, however, if you have the alternator tested off of the motor, you should be able to tell if it is working properly.

 

thank you very much

mick.

 

after a weekend on the spanners and alternator checks, it looks like the brand new battery is unservicable. returned it to the store who chenged it on sunday morning and up to now no problems.
my alternator is charging at 14.1 volts, but with all the lights and rear demister on it drops to 13.4, lights only 13.98.
so fingers crossed.

mick.