Rear end locked up? CEL: P0500 / P2404 now p0700 / U0122

[humfrz]

UGH!

You may have to get it into a dealer.


humfrz

[RZNT4R]

No need for a dealer yet, just a qualified independent mechanic.

P0700 means you've got a junk OBDII reader that can't read transmission codes. The transmission throws it's own DTC and asks the engine to throw a P0700 to light the MIL and tell people "go look at codes in the transmission".

Cheap generic OBDII readers will typically only look up engine codes. You need a scan tool with a bit more capibility. That being said, it doesn't look like your rear end is locked up, as the diff is dumb and mechanical, there's nothing in it that would cause a DTC in the transmission control system. What's going wrong is likely inside the transmission.

[maslin]

What’s wrong in the transmission is probably the unplugged ABS module. You can’t chase faults with fuses pulled out.

If the rear end is locked up it won’t roll. Can you push it a foot? Then the rear end isn’t locked up.

Probably needs to be looked at by someone with a real scan tool and some experience.

[ZOMFGAARON]

Originally Posted by maslin

What’s wrong in the transmission is probably the unplugged ABS module. You can’t chase faults with fuses pulled out.

If the rear end is locked up it won’t roll. Can you push it a foot? Then the rear end isn’t locked up.

Probably needs to be looked at by someone with a real scan tool and some experience.

Actually you can chase problems with fuses out, it’s a fairly common diagnostic strategy on multiple platforms not just ours. The canbus system is just something I’m not familiar with and it all connects back to that and how sensitive it seems to be according to multiple post.
The rear end is locked up, believe me I know what locked up means. It’s been winched onto a flatbed in neutral with the brake off and the rear end did not budge. It’s locked up buddy, I have extensive experience with cars and have a real scan tool at work but it’s the weekend and our shop is closed usually these little Bluetooth adapters work wonders clearing codes and such didn’t think the canbus system would be affected by it but I suppose I was wrong. Anything else you need clarified I’m simply asking for assistance to try and DIY fix this prior to having to it to have it towed once again this time to a shop.

[maslin]

If the rear end is locked up, why would you bother pulling fuses to disable the abs? A fault code doesn’t seize a pinion bearing.

Pulling fuses then wondering why you have can faults isn’t a diagnostic strategy.

I’ve been doing this a long time too, the only time I’ve pulled fuses to diag a car is chasing a draw. That isn’t even the “proper” way, but gets the job done.

[ZOMFGAARON]

Originally Posted by maslin

If the rear end is locked up, why would you bother pulling fuses to disable the abs? A fault code doesn’t seize a pinion bearing.

Pulling fuses then wondering why you have can faults isn’t a diagnostic strategy.

I’ve been doing this a long time too, the only time I’ve pulled fuses to diag a car is chasing a draw. That isn’t even the “proper” way, but gets the job done.

Considering the abs controls the wheels speed sensor it would cause issues with it locking up as previously stated because it thinks the wheel is going an insane speed. Unless you have any suggestions based on knowledge of our platform i don’t see any need for opinion in this thread. There’s multiple other places on the internet for you to post it.


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[Ultramaroon]

Originally Posted by ZOMFGAARON

The rear end is locked up, believe me I know what locked up means. It’s been winched onto a flatbed in neutral with the brake off and the rear end did not budge.

This is new information.

[maslin]

I’m honestly trying to be helpful. Our cars do not have electric parking brakes. With the car off, the abs is off. Reverse, neutral or drive will all be neutral with the engine off.

If the car won’t move with the key off, parking brake off, trans in anything but park, something is mechanically seized. Pulling fuses, checking codes, etc is pointless.

Every rear diff I’ve seen seize went just like you said. Driving along, starts to drag, barely make it off the road, then it’s just locked. I’ve seen it a lot of times, on various chassis. It’s a differential, there’s nothing special about it being in a frs/brz.

Every one I’ve seen lock up was due to lack of lubrication. Either a hole popped in the housing by something on the road, or a leaking cover that leaked long enough to run completely dry.

Wheel bearings tend to come apart, not seize. Same with carrier bearings. Automatic transmissions tend to lose park, not break in park. Also wouldn’t go the way you described, the parking pawl can only drop in at a low speed, wouldn’t slow you down at speed, just make that fun click click click bang noise. If the trans or driveshaft was stuck the wheels would still turn in opposite directions.

The only thing that can really stick and totally lock both rear wheels is the diff. Usually a pinion bearing gets really hot then seizes when you stop. If the gears come apart you get nasty crunch noises, or it stop suddenly at full speed.

[Ultramaroon]

Originally Posted by maslin

If the car won’t move with the key off, parking brake off, trans in anything but park, something is mechanically seized. Pulling fuses, checking codes, etc is pointless.

You have to go back and read carefully. You are correct but came in after OP followed my suggestion to isolate the issue between electronics and mechanical.

I don't know when exactly the determination was made that the rear wheels were frozen but the exact symptom wasn't clarified until this afternoon.

No harm. Zom's got this.

[ZOMFGAARON]

So I checked for leaks previously and there were none decided to flush the dif and fill it with new gear oil it fixed the rear ended being locked up still have the sensor code but I can at least drive it.


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[Tcoat]

Originally Posted by ZOMFGAARON

So I checked for leaks previously and there were none decided to flush the dif and fill it with new gear oil it fixed the rear ended being locked up still have the sensor code but I can at least drive it.


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OK I know NOTHING about the diff in this car and even less about the electronic aids but I do know that changing the oil should not free up a seized diff.
Could something have been jammed in there that came loose when the oil was changed?

[ZOMFGAARON]

Originally Posted by Tcoat

OK I know NOTHING about the diff in this car and even less about the electronic aids but I do know that changing the oil should not free up a seized diff.

Could something have been jammed in there that came loose when the oil was changed?

Honestly I’m unsure, I didn’t see any large flakes or metal in the oil when drained. I’m going to change it out again in about a week or so just to be safe and see if anything worked it’s way out.


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[x808drifter]

I read flushed diff, I don't see "Checked diff level" FIRST.

I wonder how much was actually in there.

[ZOMFGAARON]

Just an update for everyone, the dif blew up! hahah cars gone and i'm on the hunt for another one