used steering rack installed -- now dealer says it needs ECU

Did they hook up the steering gear motor power connector?

I'll check the manual for the calibration protocol this evening and post a synopsis.

Bob Wilson

 

• right side, behind to right of glove box - engine ECU, not what you want
• right side, above the engine ECU - that should be the EMPS ECU
• battery ECU - not what you want

I'm not having any more luck finding details about how to access and remove it.

Bob Wilson

 

My toyota tech friend had mentioned to me before that the standard toyota procedure for the power steering rack was to replace the rack and the ECU together. He never knew or asked why. But I guess there must be a reason, by the sound of it.

 

Maybe this is true if the customer is bearing the expense.

The power steering gear on my 2001 was replaced at 15K miles and 3 years of age, under warranty. Here are the replaced parts per the repair invoice:

44200-47060 Link Assy, Electric
95381-03028 Pin, Cotter

Then the front wheel alignment was checked.

(BTW, the four tires were also replaced at that time at no charge, under the customer goodwill policy.)

Back to Brad's OP, maybe he should buy the salvage 89661-47054 engine ECU anyway, since he may have engine no-start problems in the cold Seattle winter if that ECU revision is not already installed.

 

I've got one I need to do forensics on already but thanks for the offer.

Bob Wilson

 

Perhaps this image will be helpful - taken from the prius parts list which is in files of one of the yahoo groups. For DIY installation I think that a lot of dash removal would be required.

I don't believe that when the PS in my 2001 Prius was replaced (7/2001 mfr date), the ECU was replaced.

 

Interesting, my "Electrical Wiring Diagram" shows that as the "Body ECU:"

"Prius Electrical Wiring Diagram 2003 Model", Toyota, Pub. No. EWD493U, pp. 20.

Bob Wilson

 

I can only confuse the issue further having never actually been inside that part of the dash. Actually, your 89650- number looks good (to me) with 47190 suggesting that it is a newer version than the ones in my first picture.

Put it wherever it fits. Kidding. Put it in to replace your 89650-xxxxx.

 

I would disconnect the 12V battery, wait at least 10 minutes before pulling any connectors, and wear an anti-static wrist strap connected to the body before handling it.

 

You are at the bleeding edge of our knowledge. I didn't see an ECU replacement set of instructions and don't know if it can be done via the glovebox access or if the dash needs to be removed. Perhaps ask the guy who pulled the unit?

But then for a "sanity check," perhaps put the unit in so the connectors can be moved over and a quick drive to see if it solves the problem. That makes the task of full replacement make a lot of sense.

If you are really paranoid, pull the ground wire off of the 12 V battery and that will ensure no power. Then make sure there is a good ground wire to the case.

Bob Wilson

 

Perhaps it makes sense to understand the connectors and signals:

	Column 1	Column 2	Column 3
0	connector	pin	signal
1	A (E3)	1 white	TRQV steering shaft torque sensor
2	A (E3)	2 green	TRQ2 steering shaft torque sensor
3	A (E3)	3 black	TRQG steering shaft torque sensor
4	A (E3)	4 red	TRQ1 steering shaft torque sensor

sensors

	Column 1	Column 2	Column 3
0	connector	pin	signal
1	B (E4)	1 yellow	M1 DC motor drive
2	B (E4)	2 yellow-black	M2 DC motor drive

heavy current drive

	Column 1	Column 2	Column 3
0	connector	pin	signal
1	C (E5)	1 black	PIG power input
2	C (E5)	2 black-white	PGND power ground

heavy current input

	Column 1	Column 2	Column 3
0	connector	pin	signal
1	D (E6)	1 white-lavender	SIL data link connector
2	D (E6)	2 gray	RLY power relay signal
3	D (E6)	3 pink-blue	TC data link connector
4	D (E6)	4 black	WRR brake ECU
5	D (E6)	5 black-yellow	IG ignition switch signal
6	D (E6)	7 yellow	WL combination meter signal
7	D (E6)	9 gray-green	TB data link connector
8	D (E6)	10 white	WRL brake ECU

signals and controls

I'm thinking one way to improve 'road feel' might be to put a load resistor in the motor drive circuit. Just measure the motor resistance and then add enough to reduce the motor power to a fractional value.

Bob Wilson

 

For a favor, could you pull the ECU connector B4, the one with the yellow and yellow-black wire and measure the motor resistance?

Thanks,
Bob Wilson