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Trouble Code: U0100 ABS

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atoyot

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Discussion starter · #1 ·
Howdy.

My "check engine" light has come on and I've discovered that it relates to code U0100, which is said to pertain to the ECM's ability to communicate with one or more subsystems. The scanner shows "ABS" next to that trouble code. I'd assume that this means something like the ECM can't speak with the ABS system or something like that.

I fear this means that a shop has to be involved (..gag..). Now, when I push my brake in really hard for the "hill hold", it engages and does its job. Being as the ABS system is responsible for that feature, one might think that the ABS and the ECM are in fact talking.

Could this simply mean that an ABS sensor is not being seen? Is there a test of the ABS system other than finding a dirt road and locking up the brakes, to see if they do what they do in slippery conditions? That "hold my beer" test is available if I need to so so.

Thanks for any leads before I go and $pend money.
 
#2 ·
The code is lost communication with the ECU as you state - it is mainly a circuit code.

I would recommend you inspect the harness where is connects to the ECU and look for damage or corrosion. Which engine do you have? This is because there are different wires that provide power to the ECU, and you would need to either follow the harness to check, or use a DVOM (if you are handy with one) to check powers and grounds to the ECU.

If all these check out, it is possible the ECU has been fried.

Has anything happened recently that could lead to this problem?
 
Discussion starter · #3 ·
Bigphil555 said:
Has anything happened recently that could lead to this problem?
Click to expand...
Thanks for answering. I'm good with a meter, etc, so so no problem there. The engine runs fine.

I have the V6 on it's third transmission, and making final reduction gear noise like it would appreciate the CORRECT rebuild on that, though that's another issue. I'll have a look at the connectors under some light. Simply disconnecting and re-seating the two massive plugs that go to it did nothing.

I can't think of anything recently that would affect electrical stuff. As a ham operator, I've got a separate circuit off of the battery to my own switched sup-panel to operate VHF/UHF radios and have been doing so since buying the '09 new. All I did was start up the car one day and the light was on. If it had come on flashing, I'd be OK with that as an oil change reminder but it didn't do that.... it just stayed on full and it still does.
 
Discussion starter · #8 ·
Bigphil555 said:
@atoyot, thanks for the reply.

From an initial look at a wiring diagram, on your ECU, pin 1, white wire, should be 12v at all times.

Pin 2 and 3, black wire, should be 12v in accessory
Click to expand...

Thanks. I'll take a peek. My guess is that if the ECU has a problem, it's specific to the ABS, or, the ABS has a problem. I'll be trying electrical contact cleaner at first light tomorrow. If abusing the harness connections doesn't help it along, it may just go to a shop (preferably not the dealer; If they can't be bothered to follow their own TSB's regarding transmission work, I don't see a reason to trust them with electronics... that, too, would require following basic instructions).
 
#11 ·
On your ABS module, there are two grounds, pin 1 white/black wire, and pin 13 also white/black

There is one power, pin 2, blue wire. It is only live with key on and brake relay active (hold the brake pedal down)
 
Discussion starter · #12 ·
NameofUser said:
Ouch. 3rd transmission. I would have gotten a different car when the 2nd trans went bad.

Sorry to hear.
Click to expand...

See this bulletin. Elimination of the problem is predicated upon using a Toyauto trans rebuild with a certain designation in the part number, which reflects that the final reduction gear has been honed/machined properly. I recon that those specific rebuilt transmissions take more time to obtain, and so the stealership [twice...] ordered the standard reman units in order to get paid. Being as the standard reman transmissions had the same, improperly honed final reduction gear, they ALSO exhibited (or now exhibit) the same fu(%ing problem as the original problem.

Here's the deal: When I asked about why they ordered the transmissions without the special designation specified within the TSB above, they said, "That's the part number that warranty services aproved." True, but highly disingenuous. Having contacted the warranty services, they told me that they are NOT in the business of specifying what parts to use. They said that the dealer shop calls, describes the work, and asks for clearance to do the job using parts that the shop wants to use and the warranty office approves it if reasonable. Therefore, had the stealership been willing to wait 2 or 3 months for the correct transmission - I certainly would have been willing - the warranty office would have approved the right rebuild and I'd be on my first & likely last replacement.

When I buy my next and possibly last automobile, it'll be directly across the street from Newark Toyota (Del) at Subaru. I don't know if they're any better at this sort of thing, though their all wheel drive is a bit more serious.

Feel free to see this thread on this subject if you'd like to discuss it further.
 
#13 ·
That sucks BEYOND sucks! Criminal negligence/indifference.

Since the service dept couldn't be bothered to give a damn, a lawsuit might make them give a damn. I would have to guess it would be an easy win, b/c of that particular TSB.

Also, lemon law, three failed repair attempts, manufacture/dealer has to take/buy car back?
 
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atoyot
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