Woozy

I am trying to fix the tilt in my 1991 LS 400, when the switch is used to tilt i hear nothing, I have seen the video on the gear problem, but mine is more like there is no power so here is what i did:

I took off the covers to the steering colume to see if maybe it was binding wires, they all looked fine. I saw that there was a connector that is right above the cover to the gears for the tilt motor and goes to the columne mounted switch and back to the motor, so i figured that this was what fed power to the motor. So I disconnected the connector and checked the output side from the switch, figuring that I would see 12VDC at the 2 prongs, one for up and one for down.. well I got nothing on either one. At that point i figured that the switch was bad, because i knew power was getting to the switch as the tele fuction worked. To prove the point i decided to jump 12VDC to the connector going to the motor, assuming that it would tilt up or down depending on which pin i was on... DANG.. I got nothing doing this either... so now in TOTALLY STUMPED... I dont believe BOTH the switch AND the motor are bad... especially as the switch would only be half bad as the tele function works fine from the switch..

Is there a way to test the motor, was my thinking correct when i jumpered 12VDC to each of the pins going to the motor, or does 1 pin need ground and the other 12VDC. I assumed that ground was supplied in the motor and all I needed to do was supply 12VDC to either pin to get the motor to move.. any ideas?

twofanman

Your trouble shooting methods will not reveal the problem because the tilt switch does not have a direct connection to the motor. Both the tilt switch and tilt motor only have direct connections to the ECU. During manual operation of the tilt switch, the ECU senses which direction the tilt switch is operated. The ECU then controls the motor.

The motor only has two connections - again, both go to the ECU. The motor only sees voltage and ground from the ECU when the switch is operated (we're talking manual operation here - not auto). When the motor is commanded to operate (say in the up direction), one wire gets power from the ECU and the other wire gets a ground path through the ECU and the motor whirls away in the appropriate direction. The roles of the wires are reversed when the motor is given a tilt down command and the motor winds in the opposite direction. All of this finely engineered motor control only happens when the key is in ignition switch so that the Unlock Warning Switch is ON.

So to test the motor disconnected from the ECU, you must supply your own power and ground path to the motor. To test the output of the ECU, you must check the motor outputs of the ECU.

See the attached wiring diagram which includes operating info and troubleshooting tips. A full set of manuals is really helpful if you want to work on your car (and so cheap to obtain at TIS).

With your key in the ignition switch, you should see 12VDC between ECU A10 and ground with the tilt switch UP. You should see 12VDC between ECU A3 and ground with the tilt switch DOWN.

You can check your combination switch too. Between A3 and A5 you should see the resistances shown in the first part of the Service Hints.

The auto-memory feature is another can of worms that you can get into if need be once you confirm that you can manually operate the tilt mechanism. Let us know how it goes.

Woozy

WOW, thanks for the info!! Now i just need to know where the tilt tele ECU is

Thanks

twofanman

I tried to attach the RM pages but it failed to upload. Maybe too big. Give me your e-mail and I'll send it to you. You should do yourself a favor and buy the manuals.

Woozy

Yes i think i will buy the manuals, is it best to get them off Ebay, or what?