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Code P2603 - Hybrid system Oil Pump Motor circuit?

Tiny
SPEEDRACER3
  • MEMBER
  • 2010 LEXUS RX 450H
  • 3.5L
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 150,000 MILES
The car listed above is a RX450H, but no option was available in the drop down.

P2603 code. Followed GSIC diagnostic procedure for this code. Troubleshooting found numerous wiring faults (fixed them) and a failure at Power Management ECU output. Diagnostic procedures indicate faulty ECU. Replaced ECU with a used one - Fails again at ECU output. Replaced with a 2nd used one - Fails in the same place. I can't imagine this failure is so prevalent that I happened to get nothing but failed ECUs. I can't figure out what I could be missing.

It is probably important to note that 2 wires were open circuits (both to and from OPM relay - one supplies power to the OPM and the other was the relay trigger from the Power MGMT ECU). Additionally, and probably of some relevance. The trigger wire to the relay was one color at the ECU and another at the relay indicating a junction. However, the wiring diagrams all show 1 wire direct. Furthermore, that same wire had some resistance to chassis GND (spec is that it should be open circuit to ground). I ended up cutting the original at both ends and ran a jumper directly.

See link for diag procedure that was followed.
http://manualespurdy.cisdigital.com/Lexus/RX450h/rm2270e/MANUAL.HTM/rm2270e/repair2/html/frame_rm0000014vq00tx.html
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Saturday, August 13th, 2022 AT 1:31 PM

14 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,755 POSTS
Hi,

The diagnostics you have are the same as mine. The signal wire to the primary side of the relay shows yellow. Is that what you are seeing? If not, what colors are you finding?

Did you check if the primary side is getting a power signal? If it has power, does the white wire with a black tracer provide a ground to the primary side?

Are there any other codes?

Let me know.

Take care,

Joe

See pic below.
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Sunday, August 14th, 2022 AT 8:08 PM
Tiny
SPEEDRACER3
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Hi Joe,

The primary side does not get power. That is my issue.
I am also concerned that the wiring diagram is not accurate in terms of what I am seeing in the car. The relay has white wire for primary side and white/black for ground. White/black does provide ground, but I am not getting power on the primary side.
The ECU pin that is connected to the primary side is yellow, but somewhere along the line it changes to white at the relay. No power output at the ECU pin.

No other codes at the time, but I should scan again with the replacement ECU in case something changed.

Thanks.
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Monday, August 15th, 2022 AT 5:09 AM
Tiny
SPEEDRACER3
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Only code stored is P2601 (similar to 2603). Same diagnostic procedure.
Also, according to the wiring diagram, the power wire to the relay is BLK. Mine is BROWN. It does have battery voltage on it.
I have no 12v output on OPM2 (pin 1) and (checking with oscilloscope) no waveform signal on OPM1 (pin 33) - or OPST for that matter.
Diagnostic says Replace Power Management ECU - this is the 3rd one. How many faulty ones can I have?
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Monday, August 15th, 2022 AT 9:05 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
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Hi,

I'm sitting here thinking about this issue. By chance, could you provide the manufacturing date of the vehicle? If it is an early or late model, something may have changed.

Let me know.

Joe
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Monday, August 15th, 2022 AT 7:19 PM
Tiny
SPEEDRACER3
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I was wondering about that myself. The black nameplate on the door jamb, with the VIN on it says 10/09 in the top right. Oct/09?
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Monday, August 15th, 2022 AT 8:54 PM
Tiny
JACOBANDNICKOLAS
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Hi,

It's an early model year production vehicle. No luck. I went back a year. They are totally different. Nothing is listed for OPM doesn't show up on a 2009.

Joe.
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Tuesday, August 16th, 2022 AT 5:39 PM
Tiny
SPEEDRACER3
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So, the wiring diagrams are not the right ones for it? This is going to be fun trying to figure the ECU pinouts. All the other 3 wires line up in colors with the current data. Just the output to the relay is different (on the relay side) - the ECU side is yellow.
So, are we at a dead end?
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Wednesday, August 17th, 2022 AT 8:48 AM
Tiny
JACOBANDNICKOLAS
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Hi,

I went through two manuals and found the same thing. Something isn't adding up. According to my schematic, the wire is yellow from the ECU to the relay. See the pics below. Other than that, we are missing something.

Let me know.

Joe
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Wednesday, August 17th, 2022 AT 8:15 PM
Tiny
SPEEDRACER3
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It definitely seems like we're missing something.
Aside from this, this jumper wire I put in goes direct from ECU to Relay now. The ECU (third one) still doesn't output battery voltage to the relay. Nor does the OPM1 wire have a PWM waveform (0V).
I'm just having trouble with three ECUs having the same issue.
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Thursday, August 18th, 2022 AT 10:26 AM
Tiny
JACOBANDNICKOLAS
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Hi,

I agree. That's hard to believe, but I guess anything is possible. I realize you have run a new wire. Is power present at the ECU?

Let me know.

Joe
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Thursday, August 18th, 2022 AT 7:23 PM
Tiny
SPEEDRACER3
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I didn't test specifically for power, but it must have power because it controls a bunch of other functions necessary for starting the vehicle. I can tell you that the car won't start without it being programmed to the car. So, all 3 ECUs programmed to the car, car starts normally, enters inspection mode, no extra codes logged (which you would expect if that whole ECU was down).

But none of them trigger the relay. The OPM1 and OPST lines are consistent with the wiring diagram (color coding and continuity). Weird that just 1 wire is inconsistent.

I am thinking of reconnecting the factory wiring (removing my jumper to the relay) and seeing what happens at the relay side. The logic being that maybe we were being thrown for a loop with this relay output wire and there was nothing with it. I did find the power line to the pump motor (green) was open as well and maybe that was the only problem all along. In the diagnostic process, following the (potentially incorrect) wiring diagrams, I may have disconnected something I shouldn't have and caused another problem. Maybe that wire isn't the relay trigger (despite being yellow in the same pin location as the book says)?

Idk, seems like a stretch, but not sure what else to do short of getting another ECU - which are hard to come by (or some $1400 new).
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Friday, August 19th, 2022 AT 7:40 AM
Tiny
JACOBANDNICKOLAS
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Try reconnecting the wiring the way it was and see if that makes any difference. As far as the ECU, have you checked online? I've purchased plug and play remanufactured ones that have worked well.

It's just a thought.

Joe
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Friday, August 19th, 2022 AT 10:09 PM
Tiny
SPEEDRACER3
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I got both of the used ones online. Even those were hard to come by. I didn't see any remanufactured ones.
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Saturday, August 20th, 2022 AT 8:42 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
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Hi,

There are places that you send yours to and they rebuild it. I've used this place before. Check it out.

https://www.autopcms.com/pages/repair-center

If you were to decide to have it rebuilt, I would recommend having it done to the original one.

Let me know.

Joe
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Saturday, August 20th, 2022 AT 9:27 PM

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