LX 570 Easy access AHC (1 Viewer)

[grinchy]

No change after disconnecting the battery for about an hour. Today's mission is to find the ECU. I found where it is on a diagram (right where lx200inAR said it would be), but not sure yet how to access it.

was worth a shot.

 

[Bryanmc]

The ECU is actually a bit behind that white junction box in the video, pretty much directly behind where the third row seat folds up. It requires pulling most of the panel off.

What I’m concerned about is that it looks like someone frustratingly designed this to not be able to remove the harness plug without removing the ECU itself. I haven’t actually tried to wiggle it out but it sure it right up next to that bulkhead.

But, assuming I can get to it, it should be pretty easy to test the wiring. That might not happen until the weekend though.

 

[Bryanmc]

Well...on to next thing. Maybe your difficulty getting to the actuator is why the FSM doesn't suggest testing that connection. If you don't want to try dealer first.

First thing i would do is reconnect the actuator and reset the DTC and see if all the messing around you've done has resolved anything. It does seem convenient that you recently did a flush. Although, you said you aren't 100% sure this wasn't like this before that.


The next step is getting to the suspension ECU. It's behind the rear quarter panel on the drivers side i believe. FSM says to disconnect the connector form the ECU and from the actuator and put your tester leads on to either end. You will probably need some sort of extension or a helper.

To do test (disconnect both the ECU and the actuator plugs):
Step 1
From the ECU end, check the 4 pins in the harness going towards the actuator to make sure none of the pins are grounded (FSM calls this resistance > 10kOhm).
Step 2
From the ECU end, check the 4 pins for continuity end to end by putting one test lead on the ECU side and one on the actuator side (FSM calls this resistance < 1Ohm).
Step 3 (reconnect the actuator plug)
From the ECU end, test each of the 4 leads to ground. Should see 12 to 13.6ohm.



Steps 1 and 2
Standard Resistance:
for RH (C1733)
Tester Connection Condition Specified Condition
K31-4 (RBR-) - N5-3 (RBR-) Always Below 1 Ω
K31-4 (RBR-) - Body ground Always 10 kΩ or higher
K31-5 (RAR+) - N5-1 (RAR+) Always Below 1 Ω
K31-5 (RAR+) - Body ground Always 10 kΩ or higher
K31-13 (RBR+) - N5-5 (RBR+) Always Below 1 Ω
K31-13 (RBR+) - Body ground Always 10 kΩ or higher
K31-14 (RAR-) - N5-4 (RAR-) Always Below 1 Ω
K31-14 (RAR-) - Body ground Always 10 kΩ or higher
N5-2 (E RR) - Body ground Always Below 1 Ω <----------You already did this one

Step 3
Standard Resistance:
for RH (C1733)
Tester Connection Condition Specified Condition
K31-4 (RBR-) - Body ground Always 12.0 to 13.6 Ω
K31-5 (RAR+) - Body ground Always 12.0 to 13.6 Ω
K31-13 (RBR+) - Body ground Always 12.0 to 13.6 Ω
K31-14 (RAR-) - Body ground Always 12.0 to 13.6 Ω

I haven't done the continuity tests yet (waiting on the extensions to arrive) but I did test the ground of the ECU leads (4,5,13,14).

Both 4 and 5 give a reading of just over 12Ω when the actuator is connected and when it's disconnected.

Both 13 and 14 give me nothing in either case, just show open circuit.

Does that tell you anything?

 

[lx200inAR]

I'd be concerned that disconnecting and reconnecting the actuator made no difference. If nothing is plugged into the actuator, then you should see no continuity between any of those pins and ground and especially not 12Ohm. I say that, because assuming you were testing all the right pins and there was a short, you wouldn't see 12ohms, you'd see < 1ohm.

If you did resistance tests of Negative tester lead to a ground point and positive tester lead to the wiring harness side of pins 4,5,13, and 14 with the actuator disconnected, then you completed Step 1 from my original post. Step 3 is the same test, but with the actuator installed and you should see different results. In step 1 you should see no continuity for each of the 4 tests and in step 3 you should see 12-13.6 Ohms for each test. It sounds like you are possibly testing the wrong pins.

 

[Bryanmc]

My brain hurts. I'm using this from the FSM, as far as I know I'm checking the correct ones.

Will try again in a bit.

 

[lx200inAR]

My brain hurts. I'm using this from the FSM, as far as I know I'm checking the correct ones.
View attachment 2989077
Will try again in a bit.

I assume you are flipping them mentally, since i would guess those labels are referenced from the ECU. So if you were staring at the plug, everything would be mirrored left to right.

 

[Bryanmc]

Yep, that sounds right. Will try again.

 

[Bryanmc]

I’m certain you will think I’m a moron but here’s what I found testing the right pins (mirrored from the image above)

Actuator Connected:
5 - 13Ohms
4 - OL
13 - OL
14 -OL

Actuator Disconnected
5 - OL
4 - OL
13 - OL
14 -OL

Any of that make sense?

 

[lx200inAR]

I’m certain you will think I’m a moron but here’s what I found testing the right pins (mirrored from the image above)

Actuator Connected:
5 - 13Ohms
4 - OL
13 - OL
14 -OL

Actuator Disconnected
5 - OL
4 - OL
13 - OL
14 -OL

Any of that make sense?

Well, if you have the right pins, then the actuator connected test doesn't look so hot, although doesn't tell you whether it's the wiring or the actuator. Once you get your extensions and can test across the truck wiring, you will be able to verify you have the right pins...If you have the right pins and the wires test good, then it looks like your actuator is broken.

 

[Bryanmc]

Thanks, I’ll just be happy to figure out what the problem is. Do you happen to know what I should be searching for? I’m not having much luck with AHC actuator.

Would love to know what I might be looking at.

 

[Bryanmc]

All four continuity tests were good.

 

[lx200inAR]

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Here’s the partsouq page.

 

[Bryanmc]

Thanks. Looks like I’m looking for part # 4803060010.

Really appreciate all the help through this process, I’ve learned quite a bit!

 

[lx200inAR]

Thanks. Looks like I’m looking for part # 4803060010.

Really appreciate all the help through this process, I’ve learned quite a bit!

Well.. I’m fairly certain we followed the manual correctly, just always have a suspicion in the back of my head that’s it’s something simpler.

Seems like a lot of guys are pulling their AHC right now. Might check and see if they have the part you need. Someone just posted removing theirs in the “what have you done” thread.