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Old 10-21-2006, 03:46 PM   #1 (permalink)
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Circuit Opening Relay

I've got an '85 22re and my fuel pump is not turning on. I checked the pump and it is good. I check they efi relays and they are good. So I moved on to the circuit open relay and my manual has no information on how to test it. So I was hoping you guys might be able to tell me how. Thanks in advance.
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Old 10-21-2006, 04:22 PM   #2 (permalink)
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You can see the diagram of the CO relay on my web page:
http://www.4crawler.com/4x4/CheapTri...shtml#FuelPump

It is basically a relay with 2 coils instead of one.
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Old 10-21-2006, 07:48 PM   #3 (permalink)
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I've found most of my answers to Toy wiring here.
/forum/toyota-truck-4runner/316661-22r-22re-swap-faq.html
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Old 10-22-2006, 08:17 AM   #4 (permalink)
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Quote:
Originally Posted by 4CrawlR
You can see the diagram of the CO relay on my web page:
http://www.4crawler.com/4x4/CheapTri...shtml#FuelPump

It is basically a relay with 2 coils instead of one.
4Crawler:

Mine has started up this as well and I have been researching why.

Most FI vehicles have a mode where it brings up fuel pressure for starting. On my GM it has a time circuit that when it goes to Run on the key it powers the pump for 3 seconds to build pressure for starting. It doesn't have a AFM so its pump relay works through a Oil Pressure swtich...no oil pressure, no fuel pump.

So knowing that I am trying to find if the 22RE does something similar. Well that second coil in the relay is it. It shows trigger from the STA (Starter) circuit...thats the same Circuit as the starter crank is on. The Fuel pump is suppose to come on while cranking is what it looks like the way it seems to be wired.

I have looked at three different FSM's on cars with similar FI and its REALLY lacking in this section.

There is no good diagnostics for the second coil in the relay.

The manual shows how to test the relay coil to make sure it isn't open yes but does not have any indication of a test to verify the STA circuit is ever energized.

The Supra manual for the 7M-GE does show checking the realy by energizing it http://www.cygnusx1.net/Supra/Librar...on=FI&Page=110 But again it doesn't show a check to Verify it ever gets triggered.

What I can't find is where it gets that signal. I wonder if it comes from the starter interlock relay. What I am thinking is that the draw from the starter solenoid is dropping the voltage enough that the COR is never getting triggered.

Hepefully have some time to test it this week.
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Old 10-22-2006, 09:38 AM   #5 (permalink)
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I can't help you with the relay.
I can tell you that the fuel pump is triggered at the AFM. As I read it and understand it, no fuel pressure until you get some air flow.
No AFM = no fuel pump without alternate wiring.
You can trigger the fuel pump manually at the diagnostic port - should be info in your FSM. If you trigger it with a jumper that has a light on it (known as test probe) it'll go bright when you have igntion (key in the ON) position. It'll go out when the AFM takes over to open the circuit.

You can't hear the darn thing at all - at least I can't...
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Last edited by dcg9381; 10-22-2006 at 09:38 AM.
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Old 10-22-2006, 12:19 PM   #6 (permalink)
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Quote:
Originally Posted by dcg9381
I can't help you with the relay.
I can tell you that the fuel pump is triggered at the AFM. As I read it and understand it, no fuel pressure until you get some air flow.
No AFM = no fuel pump without alternate wiring.
You can trigger the fuel pump manually at the diagnostic port - should be info in your FSM. If you trigger it with a jumper that has a light on it (known as test probe) it'll go bright when you have ignition (key in the ON) position. It'll go out when the AFM takes over to open the circuit.

You can't hear the darn thing at all - at least I can't...
Yep you are right The AFM takes over once it pulls enough air to open but It takes fuel Spark and air to start. The jumper on the 22RE makes the connection from Pump relay to Ground So yes the light goes out once it starts because it finds another way to ground decides the light.

It has to have a way to pressure BEFORE it starts. Hence what looks like a Second trigger in the COR that looks to be triggered when The truck is actively cranking the starter.
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Last edited by Grim Reaper; 10-22-2006 at 12:23 PM.
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Old 10-22-2006, 01:00 PM   #7 (permalink)
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Pretty easy to test, just put the test jumper in and turn on the ignition. You should hear the CO relay click on and also hear the fuel pump start running if the relay is working. The STA signal comes from the igintion switch and goes to the ECU STA terminal.

Some options if the test jumper makes the relay work are to:

1. Leave the test jumper installed (I ran with the jumper in for a few years - works fine).

2. Pull the CO relay out and test the secondary winding with an ohm meter, probably should read the same resistance as the primary winding. If bad replace it.

3. If the relay tests OK, figure out why the STA signal is bad. On option is to add a starter relay (or rewire the existing relay) to take the solenoid load off the ignition switch:
- http://www.4crawler.com/4x4/CheapTri...l#OtherOptions

I basically did #1 for a few years (eventually adding a switch to the test jumper connector) then the problem seemed to fix itself, perhaps as the result of doing #3.
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