SOLVED: 100 Series overcharging issues (1998-2002 charging setups)

[cruiserpatch]

This has been documented on a few other threads but I figured I would add a definitive OEM solution for this problem.

Background:

A few weeks ago my mother's 1998 LX470 started up with an illuminated battery light. I the volt-meter in the cluster read 18V+ so I used the spare tire kit (there's a 12mm/14mm wrench in the kit) to remove the serpentine belt and drive home.

The next day I swapped out the 4-month old Autozone alternator to a spare Denso rebuilt unit I had lying around. Same problem. I tested the battery and found it to be good (also only 4-months old).

I was discouraged because I wasn't sure where to start next until I found this thread (specifically post #6). I swapped the ALT-S fuse but it did not solve the issue. Still cranking out 16V+ at the terminals with the engine running.

Then it occurred to me that I could swap some parts off my own truck and see what might happen. Sure enough upon disassembly of the N+ fusible link block, I found evidence of age and corrosion enough to increase resistance across the ALT-S circuit (and probably more than just that).

Above^ 1998 LX470 fusible link block assy.

Solution:

I replaced the entire N+ Fusible link block using these parts (available on cruiserpatch.com):

• OEM Block assembly, fusible link (1x): 82620-60010
• OEM Block assembly, fusible link cover (1x): 82621-60010
• OEM 100A fusible link, blue (1x): 90982-08246
• OEM 140A fusibile link, maroon (1x): 90982-08286
• OEM 7.5A "ALT-S" mini fuse, red (1x): 90080-82020
• OEM bolt with washer (6x): 90080-11224

I also replaced the following: (cruiserpatch.com)

• OEM N+ battery terminal (1x): 90982-05035
• OEM 12mm conductive nut (1x): 90179-08053
• OEM alternator connector: 90980-11349 (cruiserpatch.com)

On my personal truck (1999 LX470), I'm running an X2 Power AGM battery so I use this GM diode instead of the 7.5A 'ALT-S' fuse (this increases voltage to 15V max at idle).

• GM 12135037

Above^ 1999 LX470 with X2 power AGM battery and fusible link block assy. removed

 

[cruiserpatch]

Voltage with battery light on (original fusible link assembly): 16.8V

Voltage with 1999 LX fusible link assembly (swapped from my truck): 14.4V

Voltage with brand new OEM fusible link assembly and N+ terminal: 13.83V

 

[LX Cruiser]

Getting an odd, random voltage surge to 17V+ on my 570. I ordered a new alternator, but after reading this thread, I think I’ll throw a fusible link at it as well.

 

[MongooseGA]

Nice fix man. That would have driven me crazy.

 

[Live to Ski]

Patch: color me blind (not color blind...can still see the blue on the PBR label, what does that gizmo do (is it a new fuseable link)?

Also, the source & p/n of the magic potion would be much appreciated

 

[cruiserpatch]

Also, the source & p/n of the magic potion would be much appreciated

100 Series OEM Fusible link assembly kit (1998-2002)

Corroded battery terminals and old age cause the fusible link assembly to increase resistance across the charging circuit. Occasionally this creates 'overcharging' symptoms (16V+) which may damage the vehicle's battery. ih8mud thread Kit includes: OEM Block assembly, fusible link (1x)...

www.cruiserpatch.com

Will be back in stock next month

 

[rbrave]

I am about to redo my stereo, and had been planning to throw in a 4awg wire with an inline fuse.

There is an unoccupied slot in the fuseable link for a 100amp fuse - would a 140 amp fuse fit in that, and will the link accommodate 4awg wire, to have a fully stock install? Any reason I’d burn my truck down with this approach vs a more typical inline fuse?

 

[rbrave]

Answered my own question, learning about fusable links real fuses. Short story - don’t use the former outside of OEM applications, unless you want trouble!

 

[Live to Ski]

dang, i have an '04

 

[ColonelJLloyd]

Just wanted to send praise of and thanks to @cruiserpatch for diagnosing and documenting this. My trusted mechanic has my new-to-me '01 LX470 with 322k in for a once-over and called me to tell me his alternator tester is pegged and he can't quite figure out why. He's getting on in years and said, "I'm not the best Googler in the world, but maybe you can find something." Sure enough I found this thread right away.

I'm going to attempt to disassemble and clean the fusible link assembly then reinstall and test the charge. Thanks to the forum.

 

[Dirt J]

@cruiserpatch

Was the over-voltage condition persistent at any RPM? (i.e. at idle and also while driving)?

Also, did it remain at a consistent voltage, or did it fluctuate?

Trying to diagnose somewhat similar symptoms. Thanks!

 

[cruiserpatch]

@cruiserpatch

Was the over-voltage condition persistent at any RPM? (i.e. at idle and also while driving)?

Also, did it remain at a consistent voltage, or did it fluctuate?

Trying to diagnose somewhat similar symptoms. Thanks!

The overcharging was at a constant 15V+ but increased with RPMs. I thought it was a bad regulator at first but after swapping alternators and nothing changed I started digging into the charging system wiring