Where is the Circuit Opening relay located?

Hello,

Do you hear the fuel pump when the key is turned to the on position?

The fuel pump relay (circuit opening relay) is located on the fuse panel on the passenger side footwell fuse panel (see diagram below).

Here is a helpful guide on how to test the relay:

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

Please let me know if you have any questions.
Thank you.

Hello Sean M,
Thanks for responding with your answer. I did hear the fuel pump working for a couple seconds after putting in a new pump. The car would start but cut off right away. When starter fluid was used the car ran about 5 seconds longer. Next, I loosened the bolt at the top of the filter to see if fuel would come out with the key switched on. Fuel only came out when I cranked it. I'm going to look for the relay where you said - passenger side kick panel. The last time I looked, there was a mass of wires hanging out there. Thanks for the diagrams and relay testing info. I'll let you know what I come up with.

Since you are able to make it run longer with the starting fluid, the issue is likely not getting proper fuel. It is possible for the relay to cutout after a few seconds, due to having too much internal resistance.
If the relay checks out, you will have to test the fuel pressure to see if it is providing sufficient amount.

Let me know how it goes.

Hey Sean M, how are you doing? To follow-up from the last time, I found a 5-pin relay believed to be the opening circuit relay where you said it was. Based on the tests that I learned to perform it's working properly. I think your suggestion about there being internal resistance has merit. I measured the voltage at the battery and then measured the voltage across the pump connector. There was 0.66 drop in voltage between the two. This measurement was taken with the switch on and the connector unattached. to the pump. There was a 0.10 drop on the negative side and a 0.56 drop on the positive side. It was recommended to test pump voltage under load, but the pump connector is not easily back probed. I don't see how to take this reading with the connector attached to the pump. Do you think I have enough information to conclude that I have to test each circuit element to find this resistance? I don't know how to trace the whole pump circuit. Would I use a continuity tester and a test light or multimeter. I'm afraid of shorting out the PCM or computer. What do you think?

If there is too much internal resistance on the relay it will get hot much faster. Which can cause it not to work. So might want to check and see if it gets hot after the key is on for a little while.
The voltage drop is not significant enough to point to a wiring issue.

So, since you have the new pump, you can hear the pump come on for few seconds, right?

Another possibility is if the pump is functional and the relay is good, then there could be a fuel flow issue at the injectors. Which could be due to a bad fuel pressure regulator.

This vehicle should have 44-50 PSI of fuel pressure with the key on and engine off.

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

Hey Sean M,

I'm realizing that I've been taking readings across the wrong terminals to the pump connector. This led me to believe the pump was getting proper voltage when it was not. I'm actually getting zero voltage across pin 4 and 5. So, this should explain no activity with the key on. As before, the car starts but cuts off immediately. How would you proceed from here? The fuses and relays check out. Since there is no voltage to the pump through the car, how would you apply voltage directly to check that the new pump does work? Would you tap into the connector wires or jump from the battery to the male contacts at the pump?

So, if you are not getting power and you have a known good pump, and relay is good and have power, then the issue should be the wiring to the pump. It could be power wire or a bad ground, which is on the left C pillar.
I have attached the wiring schematics below.

Hey Sean M,

Just a quick summary, the car starts every time and cuts off immediately. Starter fluid helps it run longer. There is zero voltage across terminals 4 and 5 of the pump connector. I haven't found any problems with ground. But when I probed the connector to the open circuit relay one of the contacts was dead. The test light did not indicate red or green as with the others. My interpretation is open circuit in one of the wires supplying the 5-pin relay. I believe this could be the culprit. I haven't been able to get a clear diagram in enough detail to identify color and purpose of the wires going to the relay. One of the wires is always red for hot. Another wire turns from ground to hot when the switch is turned on. Could the dead wire be supplied by the ECU. How can it be checked. In which direction should I go.

Regards,
Patrick

Hey Patrick,

So, are you getting correct power to the relay?
If you have power to the relay but not out of the relay to the pump connector, then the issue would be the wire between the relay and the pump.

Have you tried to provide direct 12V to the pump and see if that makes the engine run?

Hey Sean M,

I'm reading the battery voltage at the constant power connection to the relay. For the one controlled by the on-switch, I read 11.75 voltage when battery reads 12.23 volts. The other three contacts read 0.0 to less than 2volts. When I applied direct power to the fuel pump, it did start running, but there was no pressure coming out from the filter to the fuel rail. The car did not start when jumping the pump and cranking the engine together.

The voltage to the relay is within specifications, it is not unusual to have little loss at the relay.
But if you are not getting any power to the pump, then the issue is likely a broken wire between the relay and the pump.
Check the resistance on the connector on the pump, if it reads OL then there is an open in the wire.

So, with no pressure coming out of the rail or the filter, it could either mean a weak pump or a restriction in the line or the fuel pump strainer is clogged.

Hi, I'm sorry, I'm not sure how old this thread is. I'm having a similar issue, except it seems like I'm not getting much voltage to the circuit opening relay (assuming I have the correct relay, based on the diagram). When I turn the key to the On position, I'm getting significantly less than 1 volt.

So, the circuit open relay its its power from the EFI main relay, with the key on please check both lt-grn wires at the circuit open relay they both should have 12 volts, here is the wiring diagrams so you can see how the system works and what I am talking about. Check out the images (below). Let me know how it goes

Ok, this is my first time troubleshooting something like this so please excuse all the questions!

1. Are you saying the open circuit relay gets its power directly from the EFI relay? So both relays would have to activate for the fuel pump to run?

2. If I'm not hearing the EFI relay activate, would that explain why the open circuit relay isn't activating?

3. I'm not 100% certain which relay is the open circuit relay. I think I found the correct one, based on the diagram above. The one I identified has 5 pins instead of 4, and the wires going to it are blue, not green.

4. Which pins do I check for 12v? And do I check across two pins, or from a pin to ground?

I'm at work for the day, so I won't be able to go test anything until this evening. When I get home, I'll do more testing based on your advice, and I'll also get a photo of what I believe is the open circuit relay.

Thank you so much for your help!!

Question #1 yes

Question #2 yes

Question #3 The circuit open relay should have 3 wires going to it, blu/blk, lt/grn and green.

Question #4 with the key on the lt/grn wires should have power, the blu/blk should have power as well which goes to the fuel pump, the green wire grounds from the engine computer, please upload an image when you get home and have a nice day!! Let me know.

Ok, so one more question (before I have a chance to test). If the EFI relay is also not activating, where should its power be coming from? I know the relay itself is good, as I tested it.

Ok, so the EFI relay is definitely activating. I was able to confirm that.

Here are some photos of what I believe is the open circuit relay. The wire colors just don't match what you're saying, so I'm not sure what's what.

I did some testing with my multimeter, which left me even more confused. On that relay in the photos, when turning the key to On, I do get 12 voltage on the blue/black wire. I get a good ground on the middle (white/black) wire. But on the white/blue wire, I get some grounding, but over 700 ohms of resistance, at the socket. But on the back side of the socket, I get a solid ground with almost no resistance. When I tried temporarily grounding that pin, what changes is that the fan comes on for the heating/cooling. I'm not sure how to make sense of that.

The EFI relay gets its power from the EFI fuse which is in the fuse panel under the hood. Please check the relay I have marked here.

Ok, will do! That one's harder to get to, but I'll figure something out. Thanks!

There's also a relay in a box under the hood marked EFI, which is the one I checked and found to be activating as it should.

Ok, here's what I learned.

1. That is definitely the correct relay. Thank you!!
2. When I check voltage from the lt grn to ground, I get 12v when the key is turned On.
3. When I check voltage from lt grn to green, I get about 2.5 - 3v when the key is turned On.
4. Checking resistance from the green to ground with my multimeter set to 2000k ? it shows a value of about 900.
5. When I made a temporary ground from green to ground, turning the key to On caused the fuel pump to run, but the relay still did not activate. Also, the car did not start.
6. Checking resistance on the green wire from the relay socket to the ECU socket showed 0.

Ok, I have more info and a little history on this car that I think is now relevant.

Last winter I had a similar issue with this car. Initially it did exactly the same thing: crank no-start. No check engine light. I didn't know much about it yet, so I didn't even know to listen for the fuel pump to run. Anyway, I assumed it was probably the fuel pump so I replaced it. After that it started, but wouldn't run right, and would cut out soon. I was also getting a P1300 code. I ended up replacing the coil packs, spark plugs & wires, crankshaft position sensor, and igniter, all with no change. Eventually I found some residue on the ECU circuit board. I cleaned it up, and just like that, the car ran perfectly -- for about a month and a half. Then is when this crank no-start issue came back. So I ordered a replacement ECU from Flagship One, expecting that to be the issue. When I installed it a few days ago, it made no difference. That's when I started trying to chase down this issue with the fuel pump.

Tonight, I took my old ECU and cleaned the circuit board again in the same location, because it appeared there may have been a tiny bit of residue again, but it was hard to tell. I installed it instead of the new one. With that ECU, the fuel pump started coming on every time, but still the car wouldn't start. Also, the P1300 code is back. I once again removed the old ECU and installed the new one, and it's back to doing nothing. No fuel pump. I'm starting to think there's a wiring gremlin in the wiring going to the ECU, possibly a grounding issue. Does this make sense at all? Or is it just the ECU, and the one I got from Flagship One isn't correct?

Well, this morning I installed the original ECU again. Once again, the fuel pump will run. Finally got the car started, too. I think it had just gotten flooded from the fuel pump testing we did Wednesday evening.

So at this point it feels like the ECU has to be the issue. Does that sound right?

Yep, that sounds correct. swapping ECU should not change the outcome if the ECU was not the problem. I would inspect the electrical connectors to the ECU as well, make sure they are corrosion free.