Lambda reoccuring fault- running out of ideas p3

[seanred]

my loom is almost stripped of tape at the moment so if you want to trace where each wire goes it all visible

[_Al_]

Which way do you think fingers on the lambda wiring the two black wires are attached to the ones I think are the heater element on the engine loom? What do you think?

Two black wires on mine are the heater. Try the resistance check, that should confirm it.

Next thing is to get the car running and try the lambda check at the diagnostics port. Haven't seen you mention that yet.

http://www.mr2.com/TEXT/MkII_O2_Sensor.html

It'd help you localise the problem as you can see if the wiring to the diagnostic port works then the fault must be "up-stream" towards the ECU.

[chaos19810]

Hi I haven't seen the O2 sensor check so I'll give that a go, I've brought a new multi meter so once it arrives I'll continue the search, I was thinking it might be easier to change the loom than chase a fault within the loom

[_Al_]

Best check the O2 first. It's not impossible that the fault is in the ECU...

[chaos19810]

I will be looking at the sensor check but I've just replaced the sensor from one that was working. I'll see if I can borrow a ecu and check just encase.

[chaos19810]

So I've just done the O2 signal test and it came back as normal? But still getting a fault code 21? The puzzle continues

[_Al_]

That narrows it down nicely. Wiring from diagnostics post to ECU or ECU itself.

[chaos19810]

That narrows it down nicely. Wiring from diagnostics post to ECU or ECU itself.

just changed the ecu and still got the fault so it looks like it is the wiring from the ecu to the sensor I hate wiring

[_Al_]

Continuity test between the ECU pin and the connector shouldn't take long

[chaos19810]

Continuity test between the ECU pin and the connector shouldn't take long

Just got to work which pin it is, it's the O2 in looking for

[_Al_]

Wire colour should be a clue. If not, leave one probe plugged in the wire you need to test, go to the ECU end, rattle along every pin and listen for the beep. When you've tested them all then let us know which it is.

[chaos19810]

Well I've tested the signal wire (black on the loom) to the ox1 in the diagnostic port and to the 16 pin plug and both tested ok, I did the earth (brown on the loom) to e1 on the diagnostic port and to e1 on the 26 pin plug and both were fine? That just leaves the heater wires would they cause a fault 21 before start up?

[chaos19810]

Ok now I am confused can anyone help? I've checked all the wires to the lambda and all have continuity. Today I've checked the red with and white stripe wire which runs to the ht1 pin on the ecu and the black with yellow stripe which runs to the B+ in the diagnostic port and ecu both are fine.

Now are their any other things that could cause a fault code 21? I'm lost?

[_Al_]

Check all of them for continuity to ground, just in case...