Fuel pump open circuit relay question

Fuel pump works. I only have power to one terminal at the fuel pump open circuit relay

 

Remember the cor only energizes when cranking or with the engine running.

Not like older vehicles where it would energize with the ignition in run.

You have checked all the fuses?

Any other circuits not working?

12VDC + to pin 1 the blue wire to the pump crank the engine the truck should start . If it does not you have more issues.

Up close and in person. Just how did you test your relays ?

 

Checked all the fuses all good. I think all the circuits are good got dash lights head and tail lights. I'll check for 12v at the blue wire. I swapped the relays for known good ones from my Camry. Nothing. So the truck ran fine 5 minutes before I pulled the fuel line from the filter and then pulled the FPOC relay and jumped the wrong one. It blew the efi fuse so I replaced it and hooked the fuel line back up.

 

It cranks over fine just no start

 

The relays have the same part # as the ones from the Tacoma ??

All relays are not created equal.

 

Here is a .PDF on how to check the fuel pump control circuit for a 1999 Tacoma.
It might help.

Don't skip any steps or jump around saying "I know that's good".

 

Awesome thank you

 

Same relay. When I swapped them the lights worked on the camry

 

Ok. I’ll start by saying, I am not a mechanic. I am a just your average guy that try’s to fix his own stuff.
Take my advice with caution. And do not take the information below as fact.
Everything I write below is my understanding of how the system works.
This will long, read it more than once. Do not read it at all if you don’t own equipment to test for powers and grounds.

First. Check these 2 fuses.
STA and EFI

Let’s start with how the Fuel Pump is powered.
It’s powered by the C/Open Relay AND the EFI Relay.
Initially upon cranking, the C/Open Relay is commanded On by the STA Fuse when you are cranking.

Then, once the ECM see the engine running/cranking. And you let off the key to quit cranking the engine. The ECM command the C/Open relay to stay on. It does this by using the ECM to control the relay on the ground side.

Here is how I’d diagnose it.

1. Pull the C/Open Relay
2. Check for power on Pin #2 with key On.
3. Power to pin #3 cranking
4. Ground on pin #5 alway

If you have all the above. Then it isn’t looking too good.

 

I have no power to any pins with the key on or off so havent bothered to check while cranking. I had power to the center one before I blew the fuse dont remember if the key was on or off.

 

Check for power to the EFI relay with key On. It feed power to the C/Open.

 

In post #22 you said you have power to only one pin. Has that changed?

 

I agree it certainly sounds like power was sent to the wrong place(s).

He says he jumped each pin on the relay.
Jumping Black blows EFI Fuse.
Jumping Blue send 12v straight to the ECM.

Which is basically what you said there.

 

Right. My post was wrong. Testing should be pretty straight forward though.

 

Yes, Power and Grounds first.
This whole mess started with a relay.
It would be nice if we could get a relay/fuse box diagram for the 1999
@HAVOC do you happen to have this available? I’d hate for OP to jump the wrong pins again.

 

Maybe

 

Thank you!

 

Well, Toyota as usually has you sticking things in the ECM to diag.
I guess we’ll just have to use wire colors since the Relay Pinout doesn’t show for the C/Open.
With the key ON, you need power to the White/Red wire.
I’d start there. And make sure you have a good Ground to use when testing.

 

C6 is the connector for the relay.

 

Op do you have any friends close to you that could help?

It is so much easier with the vehicle EWD in your hands.

The first thing I buy for a new to me vehicle.

When cranking the engine The COR coil pulls in the first set of contacts energizing the fuel pump.

When the engine starts the ECM sees all correct signals *** and energizes the run switch allowing the fuel pump to stay running.

***If the ECM is missing any of the signals the switch stays open the pump does not run because the ECM thinks the engine is not running.

Have any new codes tripped since the mishap??

ECM`s do not like voltage applied to the wrong place!!

One step at a time.

Good luck. If I was close I would be glad to help.