My 2000 LX 470's AHC off light is blinking and the truck is in the low position. The manual say it will automatically go into the normal ride height but mine will not. Where do I start to troubleshoot the AHC problem. My accumulators are fine. What else???

It sounds like your ahc pump is having some issues. Keep in mind that your pump motor can still run (so the fault can go undetected) but the pump can fail to move the fluids. Number of reasons cause this issue, inlcuding air creap past the shaft seal into the pump, damages pressure valve and nitrogen depletion (that last one is not likely since you mentioned that your accumulators are fine). The best way to diagnose if this is true is to manually operate the ahc pump and see if fluids are moving. If this is the case, the best solution is replace the pump sub assembly. Don't forget to bleed the system after the replacement

-Dave

[quote name='lx470tuner' post='378089' date='Jun 30 2009, 06:06 PM']It sounds like your ahc pump is having some issues. Keep in mind that your pump motor can still run (so the fault can go undetected) but the pump can fail to move the fluids. Number of reasons cause this issue, inlcuding air creap past the shaft seal into the pump, damages pressure valve and nitrogen depletion (that last one is not likely since you mentioned that your accumulators are fine). The best way to diagnose if this is true is to manually operate the ahc pump and see if fluids are moving. If this is the case, the best solution is replace the pump sub assembly. Don't forget to bleed the system after the replacement

-Dave[/quote]

Thanks Dave,
If the accums are defective will that prevent the pump from working and give me that indication? I have replaced them before with the B & B accums and I have not had much luck I think it's time for me to purchase them from Lexus. And operating the pump manually is that difficult to do and what type of equipment would I need?

Big Hurt, it is nothing to do with the AHC pump but some of the 02/03 models exhibit a flashing AHC "OFF" light with the DTC code 1743 in the AHC ECU memory. All it needs is a change to the relay unit performance.
Old Part Number - 90987-02004
Current Part Number - 89278-60010 - Relay Height Control.
For location and replacement you have to refer to the TIS manual AHC Relay location.
There was a TSB issued, maybe if somebody has can publish it for you.