Wiring Harnesses


So, the last time we spoke, I had four wheel speed sensors and a vehicle speed sensor replaced on a 2002 Sienna b/c the brake, ABS, tire pressure indicator, and engine lights were glowing, and the transmission was bucking at times. And the speedomoter was quitting periodically, too. When I picked up the car, the mechanic advised me that it might take 99-150 cycles for the computer to recalibrate itself, at which points the lights would extinguish.

Six weeks later, the TPS, ABS, and brake lights remain on. The only time they go off is first start in the morning when I drive downhill from the house. Then, about a mile later, they blip on again. The mechanic replicated the problem yesterday: lights off down hill, on when the car is level. So, he thinks there is a short in the wiring somewhere -

Any advice from anyone on how far to dig into this? The car has been in the shop for a day with no estimate of how more time he needs in sight - to his credit, he has not started billing yet -


There may be three separate problems: the TPS; the normal brake system; and the ABS (Anti-lock Brake System). You do mean the brake warning light on the dash, don’t you?
While he’s checking each wiring circuit, individually, he could check if one circuit is electrically (crossed bare wire, etc.) connecting to the others.


Yes, the warning lights on the dash - as regarding problems with individual components, the ABS system was checked, I did a comprehensive general brake job, and the computer has been cleared each time the car has been taken out for a test drive. The confounding thing is that each time the lights flick on, the computer is spitting out different codes - that, plus the fact that the lights sometimes blink off on a downhill run, makes the mechnanic think that there is a bad wire somewhere that is simply feeding the computer inconsistent bad information. The car, since the speed sensors were replaced, seems to run fine -tranny shifting as it should, speedo working and not crapping out, brakes are tighter than’s my uncle’s fist around his Blackjack winnings - but those darn lights - truthfully, I want them off so I can simply sell the darn car.


There may be a problem with the power or grounding to the control systems you mention. I would verify that those areas are ok first. I doubt there is a short or crossed wires as that may blow a fuse.