code 21
- Thread starter Late
- Start date
i tried to trace them earlier but the harness is all wrapped up and i cant see where anything goes
i dont know why you would think i was kidding. i tried to follow the wires but i cant see where they go
The ground is supplied by the ECU. No ground = no current. There needs to be at least 1 amp flowing through the sensor heater or the code gets set. Although it could be the ECU it's far more likely to be the busted wire/connection you've been told it is. You simply need to find it.
I'm done. I'd help more but IBought's avatar is too distracting...
I'm done. I'd help more but IBought's avatar is too distracting...
Little update still can't figure it out.
the ground is attached to ground point B on the side of the intake like it should be so I'm not sure why when the o2 sensor is plugged in it gets power through the ground, but I cut that wire and grounded the sensor to the chassis and still have the error. one wire is power, one is ground, and one is signal and all appear to be working as far as I can tell with my test light and air fuel ratio gauge working. I opened my ecu and I didn't see anything blown in that.
Now the weird part, I have the car off reset the codes and then turn the key to on and no codes show up, but as soon as I start my car the code 21 pops up, this is driving me crazy.
the ground is attached to ground point B on the side of the intake like it should be so I'm not sure why when the o2 sensor is plugged in it gets power through the ground, but I cut that wire and grounded the sensor to the chassis and still have the error. one wire is power, one is ground, and one is signal and all appear to be working as far as I can tell with my test light and air fuel ratio gauge working. I opened my ecu and I didn't see anything blown in that.
Now the weird part, I have the car off reset the codes and then turn the key to on and no codes show up, but as soon as I start my car the code 21 pops up, this is driving me crazy.
The round plug on the harness broke where one of the pins comes through so I pulled them out and currently have tape around them so it shouldn't be shorting there, I never took the harness off the engine during the swap so I also couldnt imagine there being a short inside of the loom across the back
I also looked up the pin out for the 89 7mgte ecu and the two wires that plug into the ecu (white and red/blue) appear fine at the plugs
I also looked up the pin out for the 89 7mgte ecu and the two wires that plug into the ecu (white and red/blue) appear fine at the plugs
Did you check for continuity at the ECU from each wire? Ground is controlled by the ECU like Jetjock said and it needs the signal as well.
Do a continuity test and report back.
Hint: Unplug both battery terminals, ground each wire and check the corresponding ECU pin for a ground.
Do a continuity test and report back.
Hint: Unplug both battery terminals, ground each wire and check the corresponding ECU pin for a ground.
I'm sorry I don't quite understand what you mean, the two wires that say o2 sensor I should check or the ground wires that plug into the ecu? I'm doing my best to understand but this problem is irritating me.
If the ground for the ecu was bad wouldn't there be other things that do not work?
If the ground for the ecu was bad wouldn't there be other things that do not work?
Good grief. How hard can it be to check continuity of one wire between the O2 sensor and ECU? And what does ground Point B have to do with it?
Why do you think that's weird?
Late;1705301 said:
Why do you think that's weird?
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Disconnect both battery terminals.
Take wire, connect to negative battery terminal.
Put other end of wire on the 02 sensor ground wire. It would be blue on the 02 side, so check the corresponding wire on the engine harness side
Check to make sure you have ground at the ECU pin of the corresponding wire.
Remove the wire from the pin you are checking, ground should go away on the ECU pin.
This is the simplest way I can think of explaining how to do this.
Take wire, connect to negative battery terminal.
Put other end of wire on the 02 sensor ground wire. It would be blue on the 02 side, so check the corresponding wire on the engine harness side
Check to make sure you have ground at the ECU pin of the corresponding wire.
Remove the wire from the pin you are checking, ground should go away on the ECU pin.
This is the simplest way I can think of explaining how to do this.
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jetjock;1705573 said:^ Huh? Now even I'm confused
^ I can agree...
Better do a "Micky mouse" & get it working because code 21 = 8 MPG or less & that is NO FUN. i guarantee it.
Now that I read it again I think the confusion lies with the words "signal wire". We already know his signal wire is good, it's his heater ground that's responsible for the code. IBought probably meant that.
Fwiw code 21 should never cause fuel economy to be that poor. Even a complete loss of sensor feedback won't do it. You must have a lead foot
Fwiw code 21 should never cause fuel economy to be that poor. Even a complete loss of sensor feedback won't do it. You must have a lead foot
I was referring to signal as the ground wire since the ECU controls it. I fixed the above post.
Sorry about that.
Sorry about that.