03 MCS Battery/Charging Circuit Woes
#1
08-02-2017, 07:06 PM
03 MCS Battery/Charging Circuit Woes
Okay, so... I haven't been on NAM in, like, five years. Long (and very sad) story short, my '04 JCW MCS was totaled and I've been MINI-less since. But that's not why I'm here now...
I'm here NOW because of an ongoing battery/charging issue on a friend's 2003 MCS. Here are the important points:
-New battery installed 7/28/17
+Lugs are clean and tight, boot wiring is in excellent condition
-New alternator installed today, 8/2/17
+Unit was bench tested in-store and passed
Also installed new belt tensioner and belt (and Max's old JCW 'charger
) while I was in there. All quality parts, all installed without any issue. Belt is the correct size for the JCW kit, and it's nice and tight, so slippage isn't our issue.
Basically, the car won't charge the battery. It starts and runs nice and smooth on a charged battery, but when charge depletes, the car dies (as expected). When it's running, pulling the positive battery terminal shuts the car off instantly- which means the alternator still isn't doing it's job. As the battery nears empty, the battery light in the speedo cluster first illuminates, then accessories start dying off one at a time, until we eventually lose fuel and spark altogether.
No relevant DTC's on the scan tool. I don't have access to a wiring diagram, but I know how charging circuits work- I'm going to test for B+ voltage at the alternator output pin tomorrow. I've been through both the driver side footwell and engine bay fuse boxes, and found no blown fuses or bad relays. Without a proper scan tool, I can't energize the alternator manually to check if the car is properly triggering it.
...so, any suggestions? My gut says it's wiring- I have my doubts that the thick charging cables are compromised, so I'm thinking it's probably something on the sensing/energizing side of the circuit. Anything specific I should check? FWIW, I've worked on VW's with a separate load sensor/voltage regulator unit independent from the voltage regulator on the alternator- the MINI doesn't use that setup, right?
Side Note: The power steering is dead, too. I've read that the PS is programmed to stop running if the alternator isn't working. So, I'm assuming they're related. Food for thought.
Open to any and all thoughts here- really hoping to nail this one and avoid sending a friend to a shop.
Cheers,
JM
I'm here NOW because of an ongoing battery/charging issue on a friend's 2003 MCS. Here are the important points:
-New battery installed 7/28/17
+Lugs are clean and tight, boot wiring is in excellent condition
-New alternator installed today, 8/2/17
+Unit was bench tested in-store and passed
Also installed new belt tensioner and belt (and Max's old JCW 'charger
) while I was in there. All quality parts, all installed without any issue. Belt is the correct size for the JCW kit, and it's nice and tight, so slippage isn't our issue.Basically, the car won't charge the battery. It starts and runs nice and smooth on a charged battery, but when charge depletes, the car dies (as expected). When it's running, pulling the positive battery terminal shuts the car off instantly- which means the alternator still isn't doing it's job. As the battery nears empty, the battery light in the speedo cluster first illuminates, then accessories start dying off one at a time, until we eventually lose fuel and spark altogether.
No relevant DTC's on the scan tool. I don't have access to a wiring diagram, but I know how charging circuits work- I'm going to test for B+ voltage at the alternator output pin tomorrow. I've been through both the driver side footwell and engine bay fuse boxes, and found no blown fuses or bad relays. Without a proper scan tool, I can't energize the alternator manually to check if the car is properly triggering it.
...so, any suggestions? My gut says it's wiring- I have my doubts that the thick charging cables are compromised, so I'm thinking it's probably something on the sensing/energizing side of the circuit. Anything specific I should check? FWIW, I've worked on VW's with a separate load sensor/voltage regulator unit independent from the voltage regulator on the alternator- the MINI doesn't use that setup, right?
Side Note: The power steering is dead, too. I've read that the PS is programmed to stop running if the alternator isn't working. So, I'm assuming they're related. Food for thought.
Open to any and all thoughts here- really hoping to nail this one and avoid sending a friend to a shop.
Cheers,
JM
#2
08-03-2017, 05:08 AM
OVERDRIVE
What voltage is being produced when the car is running? I am thinking there must be at least 13.2 volts to charge a 12 volt battery.
Also there is a fuse for the power steering pump. It is on the bottom of the engine fuse block and you need to remove the air cleaner/ecu in order to turn the fuse box over.
Also there is a fuse for the power steering pump. It is on the bottom of the engine fuse block and you need to remove the air cleaner/ecu in order to turn the fuse box over.
