Help troubleshooting ABS codes

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So, I’ll admit electrical troubleshooting is one of my least favorite things, so I’m hoping for some pointers before I dive in.

I installed a Bluetooth OBDII reader, and uploaded OBD Fusion with the Toyota package. I actually don’t have any lights, although I’ve had an intermittent Trac Off light come on when I have the center diff locked (with the normal lights). It always clears, like good electronics, with a power cycle. I’ve always wondered if my Atrac was working properly, though. I can’t say I’ve ever had it cycle, and I do a fair amount of off-roading. Now I’m slow and deliberate, but it’s always made me wonder.

So, here is a potpourri of codes. I cleared them and they all came back after 5 miles of driving. I did cycle the center lock in my field. It appears to be working fine. Thoughts?

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jerryb

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Put the volt meter on your dashboard in fusion, monitor while driving. If 1241 comes back immediately I'd hope it was just the battery being low, and or the alt not up to spec. 1241 can cause a bunch of things to trigger all by itself.

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ramangain

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So sometimes "clean and tight" at the battery terminals seems to hide a true issue of a corroded junction block that connects to the battery post. They sometimes eventually corrode and provide poor electrical contact.
 

JunkCrzr89

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So sometimes "clean and tight" at the battery terminals seems to hide a true issue of a corroded junction block that connects to the battery post. They sometimes eventually corrode and provide poor electrical contact.
Yup
 
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So, I cleaned and checked battery posts, fuse block, and junction box looks like new underneath. A bit dirty, but not corroded. OBD Fusion shows 11.7 volts when off, jumps up to 13.5 after start, then eventually settles in the 12.7 range. No variations with rpm.

So, I started to troubleshoot the ECU, and immediately ran into a problem. I have 2002 manuals, and apparently there was a change to the ECU from 2000. Can some post the DI-256 troubleshooting page for a 2000, or explain what I’m not getting? I have 4 connectors instead of the three pictured.

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Oddly, I cleared the codes, and still get all of these codes after starting, even the center diff open when I did not cycle the switch.
 
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Okay, it’s going to be one of those days. Is there a separate ABS ECU besides the one pictured (that says ABS on it…)? I see mine pictured in the ABS/VSC section.

Now I realize that first section isn’t our (US) trucks.😬
 
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Ok, so GND1 failed (resistance in the megaohms). The other 3 grounds checked good.

So…what is the approved repair? Can I splice the wire straight to body ground?

This project isn’t improving my attitude towards electrical troubleshooting at all. 😬

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Bisho, Sorry I don't have any advice to give but hang in there, you're doing great so far and you've already found a major glitch! The electronics in these vehicles is the biggest challenge, I think.
Take a breather, sleep on it (or try to anyway) and then forge ahead again with renewed energy!
 
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Maybe back to square one. I’ve Jerry rigged probes to get into the miniconnectors, but I have little faith right now I’m getting good readings. Depending on how I held the probe in that ground I could get a steady .3ohms, or a steady mega ohm reading…
Thanks for the encouragement. I need to get some better probes, I think.
 

jerryb

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11.7 volts when off, jumps up to 13.5 after start, then eventually settles in the 12.7 range.

11.7 when off after how many days sitting? cause that's bad unless it was sitting for 10+ or more days. Probably more like 30.
13.5 cold start max v charging and settling at 12.7 when idling @600+or-? if so that is also bad.
 

jerryb

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I looked at a1 and a2- pink and green, this should be your diagram. a53 is the 24 pin. checked a few of those also.
This is the diagram of what you have in your hands.

 

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Joined
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11.7 volts when off, jumps up to 13.5 after start, then eventually settles in the 12.7 range.

11.7 when off after how many days sitting? cause that's bad unless it was sitting for 10+ or more days. Probably more like 30.
13.5 cold start max v charging and settling at 12.7 when idling @600+or-? if so that is also bad.
Those values are from OBDfusion through a Bluetooth reader. The only voltage reading I can find in the options is “input voltage read by the tool”. I just checked with my multimeter, and I get 12.7v, jumps up to 14.1 after start.
 
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I looked at a1 and a2- pink and green, this should be your diagram. a53 is the 24 pin. checked a few of those also.
This is the diagram of what you have in your hands.

Thanks for this, I’ll check it later. Building a chicken coop today, and trying to find back probes for my multimeter. Amazon can get them here tomorrow, but hoping to find them locally.
 
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So, what a difference a set of back probes makes. I tested the input voltage against all of the grounds, and 12.1V at each one.
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So...replace the ECU...yay...at least I know of a truck in the pick a part and may have a shot...

But then I decided to clear the codes - up to this point the codes above kept coming back almost immediately. Well, they haven't come back, at least after a quick trip around the neighborhood. I'll get a longer drive in tomorrow. I wonder if my poking and prodding got things back in order.
 

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