DooChess

Recently bought back my 1997 LS from my father after my mother passed. Tilt didn't work well then and doesn't still. Telescope has always worked.

Gear spacing is verified good on tilt motor.

Took out both tilt and telescoping motors, cleaned the carbon out, and bench tested. Both work great and have plenty of brush life left. Reinstalled and telescope works even better now (stronger sounding motor), but tilt only works for a brief second and then cuts off. Release of the switch and repress works, albeit slower and shorter. Repeat until motor doesn't respond at all. Almost like it's missing it's juice after thermal overload somewhere?

Removed the tilt/tele switch and confirmed good. Removed tilt/tele ECU, inspected visually for leaking caps and obvious signs, but found nothing. Plugged back in and held relays on PCB while touching tilt up/down. Audible and felt clicks.

A search showed people saying their tilt/tele ECUs never go bad, but I'm at a loss as to what else I could be dealing with other than some PCB related issue.

Before I send the PCB in for diagnosis to a repair facility on my feelings, does anyone have any thoughts?

Summary - Tilt works only momentarily until what I can only describe as losing power, bench tested fine at constant speed OK, switch good, relay 'clicking.'

PS - No write-up exists on removal of these motors that I could find. I will commit to writing one if/when I can get this issue solved.

DooChess

Did some testing as shown in the FSM. Markings in red are outside tolerance. If no markings, within spec found.



6.488kΩ found. Slightly out of tolerance. Shouldn't be too worried about it.



1.9Ω found. Near double the resistance suggested within tolerance. Not sure I should be too concerned, however, since telescope functions perfectly with resistance as is.

The issue being tied solely to the tilt is what baffles me.. Has to be something on the PCB in that circuit only!

DooChess

More findings below;



All passed here..



All measurements within parameters..

DooChess

Backprobed the leads going into the motor from the ECU and on motor side and am getting 12V temporarily which would make sense since the motor works and then stops.

I can only deduce that my trouble is between ECU to motor since I'm not getting 12V constant when pressed. Gotta be a capacitor, right? If the capacitor isn't building enough of a charge to spin the motor up to working RPM, the motor will shut down. Also would explain the description of it working for a second if left alone (larger charge in capacitor) and slowly degrading with each consecutive push (no charge left only line voltage).