HELP! AHC fault after globe replacement (1 Viewer)

[Burley]

I replaced my accumulators tonight but missed the step about having to have the system in LOW mode before starting. I drained and replaced the accumulators in NORMAL mode. Now when I start the truck it flashes N then says Low and gives the Check 4 Wheel AHC system. The pump won't run. I've tried disconnecting the battery for awhile and get the same result. I can't get it to forget Normal mode.
Any suggestions? TIA

 

[GOLIGHTLY]

I replaced my accumulators tonight but missed the step about having to have the system in LOW mode before starting. I drained and replaced the accumulators in NORMAL mode. Now when I start the truck it flashes N then says Low and gives the Check 4 Wheel AHC system. The pump won't run. I've tried disconnecting the battery for awhile and get the same result. I can't get it to forget Normal mode.
Any suggestions? TIA

There’s a procedure outlined on here in one of the AHC globe posts. Something like “turn the truck off and hold the toggle up in the raise position while you turn it back on”.

 

[Burley]

There’s a procedure outlined on here in one of the AHC globe posts. Something like “turn the truck off and hold the toggle up in the raise position while you turn it back on”.

I tried that multiple times as well. I saw it on a couple videos and posts but no luck. I read somewhere that only worked on the 100 series.

 

[GOLIGHTLY]

I tried that multiple times as well. I saw it on a couple videos and posts but no luck. I read somewhere that only worked on the 100 series.

I just did this job on my 200 a month ago, did take me a few tries though. I’m in the car otherwise would dig and find the thread for you. Someone help me out

 

[grinchy]

How much fluid is in the reservoir?

If the car is drivable go put 5 miles on it.

There are some Ahc test modes in tech stream.

Hookup a code reader and see if you have any codes. Add them here.

Reset the codes while you’re in there.

 

[lx200inAR]

I assume you added new fluid to the system. Did you check the fluid before adding it? Was it in metal can or plastic 1L bottles? If it was metal cans, probably not a big deal, but if it's plastic bottles, you should look to see if they have a clearish glob in the fluid.

Did you replace all 4 globes at the same time? When you do this, you are asking the system to replace a lot of fluid. It can take quite a few cycles to get everything back in order. When I did mine, I replaced one globe and then let the pump get that corner back to normal, then moved on to the next globe. Being in N or L doesn't matter that much when it comes to changing the globes. You just lose more fluid if you are in N when you bleed off the pressure of a corner initially before changing the globe.

As stated above, you should probably see what code is throwing the AHC error in the dash. Most likely an abnormal pump pressure, but best to check. Hopefully clearing that will get the pump running again.

Something I've found when the pump needs to draw a lot of fluid is that you will get a vacuum in the reservoir. If you pull the plug that you use to fill the reservoir you will break that vacuum and the pump will usually get going again, assuming you've reset any codes that are causing the pump to not run.

 

[Burley]

I ended up getting it this today. Thanks for all the help everyone. After letting it sit all night it finally recognised that it was Low and allowed me to adjust the height.

 

[NKP Garage]

Glad you got it fixed. I've done this a few times now. After globe replacement what I do is start the truck, and as soon as i'm starting it I continuously keep flipping the up/down switch to the "up" position, keep flipping it until you see the display showing that it is rising. Then let it do it's thing for 5+ minutes. Let it sit and keep running. After its been in the up position for a few minutes then drop it to the lowest position, let it sit there for a few minutes. Then to N, then to H again, then to L, and then finally back to N. Leave it at each position for a couple minutes. After that, go drive it around for 10 minutes, come back to the house and then go through H, L, N, H, L, N. Then shut it off in N, check your fluid level, and correct it if necessary. A little overkill, but this way you make sure its all good and ready to go for a long time without having to worry about it again.

 

[GOLIGHTLY]

I ended up getting it this today. Thanks for all the help everyone. After letting it sit all night it finally recognised that it was Low and allowed me to adjust the height.

The ol “put it in time out, and let it think about what it did”. Love it.

 

[lx200inAR]

Glad you got it fixed. I've done this a few times now. After globe replacement what I do is start the truck, and as soon as i'm starting it I continuously keep flipping the up/down switch to the "up" position, keep flipping it until you see the display showing that it is rising. Then let it do it's thing for 5+ minutes. Let it sit and keep running. After its been in the up position for a few minutes then drop it to the lowest position, let it sit there for a few minutes. Then to N, then to H again, then to L, and then finally back to N. Leave it at each position for a couple minutes. After that, go drive it around for 10 minutes, come back to the house and then go through H, L, N, H, L, N. Then shut it off in N, check your fluid level, and correct it if necessary. A little overkill, but this way you make sure its all good and ready to go for a long time without having to worry about it again.

I definitely agree and think there is a real benefit to following a process like this. Even if the system fails to get to the height called for, as long as it doesn't throw an error and go to AHC OFF, it will keep cycling to try to get everything where it wants it. It won't show anything in the dash, but the pump will run in stints of 30-60 seconds (i can't remember how long now, it's been a while) while you are driving until it finally gets to the height it wants. Then I think the cycling between H, N and L does most of the bleeding that needs to happen.

Now that I have OBD Fusion setup to monitor the AHC ECU, I will never work on AHC without using the monitor. It gives you far more insight to what the ECU is doing than the combimeter screen ever will. You can accomplish this with Techstream as well, but it's easier for me to monitor in OBD Fusion.

 

[chriscosta416]

From swapping out globes on a few LXs, this usually happens when you bleed too much from the bleed valves at each corner, I think a quick bleed at each corner is good, then pull globes.

For those have have techstream you can manually actuate the valves and that will usually resolve the issue.

 

[bruisecruise]

I'm pretty sure using the 'Active Test' feature in TechStream for changing front or rear height will run the pump regardless of fault codes, I've used it to prime after changing globes when clearing the codes multiple times was taking too long.