Power Steering Light

[sıɹɐʎ]

My P/S light came on yesterday. I'm pretty sure it started when I was turning at 5mph on a steep incline. Power steering appeared to still be functional, although I was driving at low speeds. I went and parked at work; when I restarted the car, the light was off.

Unfortunately I don't have a ODB-II reader. My immediate thought was the power steering fluid, but the factory service manual makes no mention of fluid as a direct cause for the light to go on. Moreover, the failsafe chart suggests that "asssist force restricted" is generally applied due to electrical problems rather than mechanical ones.

My '07 Yaris is a little over 25,000 miles, and I'm taking it in to the dealer for scheduled service this Saturday, so I thought I'd have them look at it. Before I go, I was wondering if anyone had any similar stories (I couldn't find any when I searched) or suggestions. Thanks!

[CTScott]

An OBD reader wouldn't help, as they can only read codes from the ECM, not from peripheral ECU's like the power steering ECU.

You can read the DTCs of the PS ECU by flashes of the PS light by doing the following:

1. With power off, connect terminals CG, TS and TC on the DLC3 connector (using jumpers).

29724

2. Turn the ignition switch to the on position.

3. Read the number of times that the P/S warning light on the combination meter blinks.

• To indicate the normal code, the P/S warning light comes on for 0.25 seconds at intervals of 0.25 seconds (2Hz blink).

• When outputting a DTC, the P/S warning light displays it at intervals of 4 seconds. When outputting two or more DTCs, the P/S warning light displays each DTC at intervals of 2.5 seconds, and repeats from the first one 4 seconds after indicating the last one.

• If two or more malfunctions are detected at the same time, DTCs are displayed in ascending numerical order.

29725

[sıɹɐʎ]

You can read the DTCs of the PS ECU by flashes of the PS light by doing the following...


Thanks, Scott! I saw this in the manual but I wasn't sure how to proceed without the intelligent tester. I'll try this as soon as I get home from work. My manual states that I should connect CG and TC to check and CG and TS to clear.

One thing I'm still not quite clear on is how to translate the codes. The way I understand it is that if it posted a 12, it would imply Diagnostic Trouble Code C1512/12, 24 would be C1524/24, and so forth. Is that correct?

[CTScott]

Thanks, Scott! I saw this in the manual but I wasn't sure how to proceed without the intelligent tester. I'll try this as soon as I get home from work. My manual states that I should connect CG and TC to check and CG and TS to clear.

One thing I'm still not quite clear on is how to translate the codes. The way I understand it is that if it posted a 12, it would imply Diagnostic Trouble Code C1512/12, 24 would be C1524/24, and so forth. Is that correct?

Correct.

[sıɹɐʎ]

Well, it appears to have posted codes 91 and 92, but I can't find any reference to them in my manual.

I think I'm reading the codes properly, but I've made a video in case I'm off mark.
http://www.youtube.com/watch?v=pnHlvsqR-Wk

Any help or suggestions would be appreciated, as always. Thanks!

[CTScott]

I see them as 91 and 92 as well. Even in the 09 manual there is no reference to those codes.

I did notice that in the 09 one it only says to connect CG and TC (no TS) to read the codes. You might want to give that a try, just in case the three connections was a misprint in the 07 manual.

[sıɹɐʎ]

I see them as 91 and 92 as well. Even in the 09 manual there is no reference to those codes.

I did notice that in the 09 one it only says to connect CG and TC (no TS) to read the codes. You might want to give that a try, just in case the three connections was a misprint in the 07 manual.

Yes, that's what I did -- just CG and TC. According to the '07 manual, connecting all three is done to read test code mode.

The P/S light went on again tonight on the way home as soon as I started the car. I stopped and checked the codes immediately -- 91 and 92 again. This got me to thinking... there are three ECU codes for connection with the ECM with DTCs unlike the others: U0073, U0105, and U0121. It also states "When two or more DTCs starting with [U] are output simultaneously, inspect the connectors and wire harness of each ECU."

I accidentally did some slight damage to the plastic white connector on A21 when I was installing cruise control recently, but I didn't think much of it. I wonder if this might be related. I'm going to double-check it.

UPDATE: I pulled A21, inspected it, pushed locking mechanism back in fully, and reattached. So far no trouble. I am going to have the dealer read the code with the intelligent tester when I take it in for the 25,000 mile service this coming week. I'll let you all know what they say -- hopefully it may help someone else with the same problem searching the boards down the line. Thanks again for all the help so far!

[sıɹɐʎ]

UPDATE: I pulled A21, inspected it, pushed locking mechanism back in fully, and reattached. So far no trouble. I am going to have the dealer read the code with the intelligent tester when I take it in for the 25,000 mile service this coming week. I'll let you all know what they say -- hopefully it may help someone else with the same problem searching the boards down the line. Thanks again for all the help so far!

I haven't had any further problems with the Power Steering light since I did this. (My cruise control is still working perfectly.) I will still get the dealership to use the Intelligent Tester during my 25,000 mile service this Friday.

[sıɹɐʎ]

I went to the dealer and their response was "the intelligent tester won't help. If the light isn't on now then everything is fine." I didn't have the service manual with me, but unless I'm pretty sure that it describes how to use the intelligent tester to read the trouble codes from the Power steering ECU. Am I wrong?

[CTScott]

I went to the dealer and their response was "the intelligent tester won't help. If the light isn't on now then everything is fine." I didn't have the service manual with me, but unless I'm pretty sure that it describes how to use the intelligent tester to read the trouble codes from the Power steering ECU. Am I wrong?

It looks like once the light is off, the DTCs are all cleared.

[higadogt]

I got same problem P/S light pop up but nothing else happend, i just test with light like u explain ans i hoy error 91 how o fix tht can u help me plz?

[CTScott]

I got same problem P/S light pop up but nothing else happend, i just test with light like u explain ans i hoy error 91 how o fix tht can u help me plz?

As mentioned above, code 91 is not shown in the service manual, but it looks like it was related to communications with the ECM. Try checking and reseating the ECM connector (the smaller one of the two) as that solved it for the person above.

[higadogt]

I will try, ty vm and worry for my english still learning