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Old 06-11-2013, 01:37 PM   #1
nitrus10032
 
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2007 sedan fuel pump not running and check engine light

I have a 2007 Yaris Sedan (Not S). Yesterday it took quite a while to get started. When I put the key into the ON position I don't hear the fuel pump engage and the check engine light is on. After it started once it didn't have problems starting again. The check engine light also shuts off once the car is started. I hooked up an ODB2 scanner and there were no codes when the car was in the ON position and when started.

Based on what I've read on the forums it's a fuel pump/filter issue. Is there anything I should check besides that and is it necessarily the pump itself or could the filter also cause this issue?

Additionally, is it safe to keep driving the car with the pump in this state? My guess is killing the battery is the biggest risk since on occasion I have to hold it in the start position for longer than normal.

Mileage: 118k
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Old 06-11-2013, 02:30 PM   #2
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The fuel pump power is switched by both the EFI and C/OPN relays (both of which are part of the integration relay assembly in the under-hood fuse panel). That module would be the other thing that I would suspect. If you have a multimeter, I can walk you through how to test the two relays within it.
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Old 06-12-2013, 12:11 AM   #3
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I've got a multimeter and the integration relay pulled out. Would either of those relays being bad still allow the car to run?
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Old 06-12-2013, 06:36 AM   #4
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If the relay contacts are intermittently contacting, then the car would still start some of the time.

Integration Relay.jpg

The EFI relay is in the integration relay. It's coil is connected to pins 2 and 3 of connector 1A. If you measure the resistance between those two pins you should a resistance under 100 ohms.

If that looks fine, you can fire the relay using a 9 volt battery and two pieces of wire. Connect one terminal of the battery to pin 2 and the other to pins 3 and you should hear the relay click closed.

Pins 1 and 4 are the contacts. With the relay powered you can measure the resistance between those two pins and they should be a short (0 ohms).




The C/OPN relay is actually not within the integration relay, but rather is in the body ECU assembly (within the guts of the under dash fuse panel).



The coil of the c/opn relay is connected to pins 4B-9 (red wire) and 4E-5 (violet wire). With the ignition off, if you measure the resistance between those two pins you should measure under 100 ohms.

The contacts are connected to pins 4A-8 (black wire) and 4B-11 (black wire). With the ignition in the ON postion, measure the voltage on the pin 4A-8 and you should see 12-14V, if the relay is closing properly.
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Old 06-13-2013, 09:17 PM   #5
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Thanks for the help!

It looks like the integration relay is working fine. The resistance across all sets of relay pins is ~330 ohms however. But apply the 9 volts to each closes them and gives me continuity between the pins.

The C/OPN tests don't look good though. There appears to be no continuity between 4B-9 (red wire) and 4E-5 (violet wire). When the engine is in the on position and I've connected one lead of the multimeter to 4A-8 and the other to my battery's negative terminal there is no voltage. So it appears the C/OPN relay is the problem.

Is that part replaceable or does the whole assembly have to be replaced? Do you have the relevant part numbers?

Again, thanks a ton for your help!
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Old 06-13-2013, 09:37 PM   #6
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Originally Posted by nitrus10032 View Post
Thanks for the help!

It looks like the integration relay is working fine. The resistance across all sets of relay pins is ~330 ohms however. But apply the 9 volts to each closes them and gives me continuity between the pins.

The C/OPN tests don't look good though. There appears to be no continuity between 4B-9 (red wire) and 4E-5 (violet wire). When the engine is in the on position and I've connected one lead of the multimeter to 4A-8 and the other to my battery's negative terminal there is no voltage. So it appears the C/OPN relay is the problem.

Is that part replaceable or does the whole assembly have to be replaced? Do you have the relevant part numbers?

Again, thanks a ton for your help!

That would be bad. If you have no continuity on the coil, then it should not start at all.

The C/OPN relay is not replaceable as it is seriously buried within the bowels of the body ECU assembly. There are quite a few part numbers for each year, based on number of doors, power locks or not, etc. If you want to PM me your VIN I can tell you which your car has, or you can stick a mirror up behind the body ECU to read the label on the back of it.

New ones are crazy expensive (~$700), but used ones can be purchased for under $100 from junk yards. I have one off a 2008 sedan that I picked up from a local junkyard for $75.
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Old 01-06-2014, 12:46 PM   #7
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I know this is an old topic but my 2007 Yaris is doing the exact same thing. This is my first post and so far this forum has been the only source online that has been of any use in fixing my car myself.

I've gone through and tested as you described and I'm getting no voltage on pin 4a-8. I was hoping that, you could tell me if replacing the body ecu fixed your problem? If the body ecu is part of the fuse box under the drivers side dash? And finally at the fuel pump, which wire is the positive an negative so I can test the fuel pump to confirm operation.

Thanks in advance!
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Old 01-06-2014, 12:59 PM   #8
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Originally Posted by Edmond View Post
I know this is an old topic but my 2007 Yaris is doing the exact same thing. This is my first post and so far this forum has been the only source online that has been of any use in fixing my car myself.

I've gone through and tested as you described and I'm getting no voltage on pin 4a-8. I was hoping that, you could tell me if replacing the body ecu fixed your problem? If the body ecu is part of the fuse box under the drivers side dash? And finally at the fuel pump, which wire is the positive an negative so I can test the fuel pump to confirm operation.

Thanks in advance!
I never heard back as to if the body ECU was replaced to resolve it. The body ECU is part of the under-dash fuse panel. There are many different part numbers for the body ECU, so you would need to check which your require via the part number on the back of it. The label is on the back side facing the firewall, but you can stick your phone back there to snap a picture. I can also check by your VIN number (you can PM it to me if it gets to that).

For the wires on the fuel pump itself, the black wire is +12 and the white/black is ground.
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Old 01-06-2014, 02:55 PM   #9
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Thank you so much, I'll send you the vin after I double check my work.

Thanks again!
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Old 01-07-2014, 03:06 PM   #10
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I was able to double check pins 4B-11 and 4A-8. With Key ON, there was 12v at pin 4B-11 and nothing at 4A-8. I threw 12v to the fuel pump and I could here it run. I checked continuity between pin 4A-8 and the black wire at the fuel pump under the back seat and it appears to be the same wire.

I tried to start the car while supplying 12v to the fuel pump to no avail. The car has had this problem since Christmas so It may just need a little motivation with this Negative degree weather we are experiencing here in Kentucky.

I am very familiar with auto electrical systems and my question is, can I bypass the C/OPN relay by using the pins you provided and adding another relay?

I'm sending you my vin for the Junction block part number in case that's the route I need to take.

Thanks again!
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Old 01-07-2014, 03:25 PM   #11
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Originally Posted by Edmond View Post
I was able to double check pins 4B-11 and 4A-8. With Key ON, there was 12v at pin 4B-11 and nothing at 4A-8. I threw 12v to the fuel pump and I could here it run. I checked continuity between pin 4A-8 and the black wire at the fuel pump under the back seat and it appears to be the same wire.

I tried to start the car while supplying 12v to the fuel pump to no avail. The car has had this problem since Christmas so It may just need a little motivation with this Negative degree weather we are experiencing here in Kentucky.

I am very familiar with auto electrical systems and my question is, can I bypass the C/OPN relay by using the pins you provided and adding another relay?

I'm sending you my vin for the Junction block part number in case that's the route I need to take.

Thanks again!
The C/OPN relay is just an ignition switched power relay that only switches power to the fuel pump, so you could indeed bypass it with a relay.

The coil would be fed by 4B-9 (+12) and 4E-5 (ground switched by the ECM).
The contacts would be connected to 4B-11 and 4A-8.

As one final test to verify if the C/OPN relay is the problem or if the ECM is, check the voltage 4B-9 and 4E-5. If they are both 12 volts, then the ECM is not bringing 4E-5 to ground to complete the circuit for the relay coil.
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Old 01-07-2014, 05:25 PM   #12
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I will check this tonight to confirm. I got your message and thank you for looking.

To help others who may have a similar problem, this started after someone had borrowed my car and left the dome light on overnight. They tried to jump start my vehicle and they think they crossed the jumper cables but are not sure. It may be unrelated but don't know for sure. One fuse was blown for the ABS but my abs light had been on so I assume it was unrelated. I am getting spark at all four cylinders but I have no fuel pressure.

I will let you know my findings.
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Old 01-15-2014, 09:45 PM   #13
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I got really busy with work for the last week and was unable to check the voltage at the pins until tonight. Both pins had 12v with the key in the on position. Is this a sign of a bad "body ECM" or "engine ECM"?

NOTE: I started getting 12v at pin 4a-8 after throwing 12v to it a few times trying to get it to start. Any advice with this.

Thanks again.
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Old 01-15-2014, 10:51 PM   #14
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Originally Posted by Edmond View Post
I got really busy with work for the last week and was unable to check the voltage at the pins until tonight. Both pins had 12v with the key in the on position. Is this a sign of a bad "body ECM" or "engine ECM"?

NOTE: I started getting 12v at pin 4a-8 after throwing 12v to it a few times trying to get it to start. Any advice with this.

Thanks again.
If 4B-9 and 4E-5 were both at +12 then the ECM was not pulling 4B-5 to ground, so I would say that the ECM is at fault. That also would explain why it still wont run when you manually power the fuel pump.
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Old 01-17-2014, 12:19 AM   #15
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Thanks CTScott, is the part number you gave me the ecm I need?
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Old 01-17-2014, 07:29 AM   #16
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Thanks CTScott, is the part number you gave me the ecm I need?
Yes.
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Old 10-26-2014, 08:13 AM   #17
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I just stumbled up this thread as my wife's car is showing the same symptoms - cranks and doesn't start. I followed the instructions above and got the following:

Testing the coil of the c/opn relay on pins 4B-9 and 4E-5 with the ignition off got a resistance of 170ohms.

Checking across pins 4A-8 and 4B-11 with the ignition in the ON postion I found the voltage to be 0. If checking the same pins individually with the multimeter grounded on the chassis I found 12v at both pins.

I then shorted the 4A-8 and 4B-11 and when trying to start I could smell unburned fuel coming from the exhaust but it still wouldn't start.

Do you think I'm looking at a faulty ECM and do I read right that the relay is integral to is and cannot be replaced without replacing the ECM itself? If this is the case where would I find it to get a part number or can it be found from the VIN?

Many thanks for any help you can provide :-)
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Old 10-26-2014, 11:09 AM   #18
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Originally Posted by Gander View Post
I just stumbled up this thread as my wife's car is showing the same symptoms - cranks and doesn't start. I followed the instructions above and got the following:

Testing the coil of the c/opn relay on pins 4B-9 and 4E-5 with the ignition off got a resistance of 170ohms.

Checking across pins 4A-8 and 4B-11 with the ignition in the ON postion I found the voltage to be 0. If checking the same pins individually with the multimeter grounded on the chassis I found 12v at both pins.

I then shorted the 4A-8 and 4B-11 and when trying to start I could smell unburned fuel coming from the exhaust but it still wouldn't start.

Do you think I'm looking at a faulty ECM and do I read right that the relay is integral to is and cannot be replaced without replacing the ECM itself? If this is the case where would I find it to get a part number or can it be found from the VIN?

Many thanks for any help you can provide :-)

Cranking and not starting can also be an immobilizer issue, particularly with you smelling the unburnt fuel when bypassing the C/OPN relay. There is an indicator light that flashes when you turn the car off to say that the engine is immobilized. When you stick the key in the ignition the key's transponder is read and the ECM turns off the immobilizer indicator if it likes the code from the key. Check that indicator first (as I have spoken with quite a few people with European Yaris that have had issues with the ECM suddenly deciding that it doesn't like a key). If you have extra keys, try those as well.

With the C/OPN relay, it is part of the body ECU, not the ECM. So, if the relay is bad, you do have to replace the body ECU to replace the relay or simply bypass it with an external relay.
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