With such a long run time, something is wrong. Perhaps a leaky check valve in the HPU pump body. You could watch techstream “data list” to verify that pressure is actually building slowly, and not just a bad pressure sensor.
Paul, HPU runs more than 30 sec (nearly a minute) now. But I cannot find any leaks. Is the HPU needs rebuilding or the GSU? Or should I rebuild both? Thanks.
I wrote overhaul procedures with lots of photos for both the GSA and HPU. I’ll try to post here. They are google document files... docs.google.com/document/d/1Jfhl7acmOMXR6GbovRsgh95gWVvryQNtvivFk-tu7_4/edit docs.google.com/document/d/1UU75bsHez5A5wlzYabLiLAa87_yngMZURuuvBDCSzZA/edit docs.google.com/document/d/1Aw7X34PTc_lcaOdSnhAIf9I3uMM1BsfQNvhMixYfAq4/edit
Try tasting the $107 fluid. What does it taste like? Brake fluid! Try looking at the black sticker on the HPU and GSA solenoids on your SMT. All four of them. They all say “brake fluid” in big silver letters. Those stickers were applied by LUK, the manufacturer of the entire SMT system.