I would disconnect the o2 sensors and check your live data. If it doesn't change and the figures are the same as before then it could be an ecm issue.
If the figures/codes change then the o2 sensors/wiring are at fault.
The ecm may or may not work.
Before plugging the replacement in carry out the test with o2's umplugged
If the figures/codes change then the o2 sensors/wiring are at fault.
The ecm may or may not work.
Before plugging the replacement in carry out the test with o2's umplugged
As said above, when changing GEMS ECU you need to re-sync GEMS to the BECM. If you simply swap them without doing any re-sync the spare will NOT work, but the original should still have the matching code to the BECM.
Regarding disconnecting the O2 sensors, yes you can. In this case the GEMS will simply use default fuel settings. You will also get O2 sensor faults logged !!
Remember your original faul was P0605 which is faulty ROM in the GEMS ECU.
1) Check if your iCarsoft actually has the re-learn option in the GEMS utility menus ? (if not you need a Nanocom)
2) Install the spare GEMS ECU
3) Ignition on, but don't try to start yet.
4) In GEMS Utility tell it to re-learn the code from the BECM
5) Car should now start as normal
6) Next re-connect the O2 sensor, and reset adaptive values in the GEMS ECU & drive the car 10-30 miles !!
Here's is a summary of the GEMS re-learn function from Nanocom guide.
If iCarsoft does not support these, you are stuffed.
Thanks for the answers! I'm testing without O2 sensors.
To clarify or confuse, the O2 values when testing before wandered recklessly, changing from one reading to another within a second, between 1.5 and 320.52V. The wires are fine from the ECM to the O2 connectors, resistance values 0.1ohm. Meter Fluke 365.
To clarify or confuse, the O2 values when testing before wandered recklessly, changing from one reading to another within a second, between 1.5 and 320.52V. The wires are fine from the ECM to the O2 connectors, resistance values 0.1ohm. Meter Fluke 365.
You must have something wrong with how you are measuring them ? The O2 sensors can only swing from 0V to 5V !!
320V is not normally possible. If they did reach this voltage, it would explain the GEMS ECU failure !!
The o2 sensors should waver. The pré cat o2 sensors reflects the oxygen rate being lowered and raised to boost the cats efficiency.
The post o2 sensors when fitted reflect the cats ability to react to the oxygen levels when burning the gasses off.
The post o2 sensors when fitted reflect the cats ability to react to the oxygen levels when burning the gasses off.
I don't think the icarsoft is an exact match for your diag requirements matey 
+1 on that. Looking at the videos & info out there, $h1tpart basically took a generic OBD reader, and got a 3rd party to make it look like an LR diagnostic. The "coverage" is vague at best, and after a few years they charge annual subscription, so not long before you're paying more than a Nanocom !!I don't think the icarsoft is an exact match for your diag requirements matey
Yes, I feel the same way about the abilities of that Icar tester. Another thought is that the ECM is damaged, which the home p0605 has already determined, and this, along with the outdated O2 sensors, is possibly running something of a loop not knowing what to do with the readings. If so, Icar may be able to show the event. My car has 2 O2 sensors before the catalytic converters. I'm also under the impression that the immobilizer has been removed. How, I have no idea. There is also some extra wiring, as well as broken wires near the BeHM terminals. So the original instructions may not apply to this car.
The ECM wiring is original and matches the diagram.
The ECM wiring is original and matches the diagram.
For the GEMS O2 sensors, you're better off using a generic OBD tool with graph displays. I use one of these dongles with either iPhone/iPad or Android phones & tablets. Car Scanner Pro works really well and has free & paid version.
It reads & shows live engine data much better than my Nanocom (although that's best for everything else). FYI The reason Nanocom struggles with O2 sensors is the slow CPU it contains !!
Optiuons & live data example (short term trims & O2 sensor voltages)
It reads & shows live engine data much better than my Nanocom (although that's best for everything else). FYI The reason Nanocom struggles with O2 sensors is the slow CPU it contains !!
Optiuons & live data example (short term trims & O2 sensor voltages)
Last edited:
My multimeter for car use is the Fluke 365, true rms clamp meter.
I measured again with obd scanner, Icar, Ox sensors disconnected.
Results: Bank A Ox 316.25V varies. Bank B 229.90V varies. Ox heater 15.06 Ox sensor heater 46592%.
Ox sensor configuration, No Sure. Idle reference speed 48130. Ox sensor open circuit has been added to the fault codes, which is true, they are disconnected in this test. Bank A and B values are the same whether the Ox sensors are connected or not. Conclusion: Ox circuits are open in the sensors. The heating used to be low resistance, now it is open, so its detection by the ECM exists. Well, the car hasn't been used for 10 years at the mercy of the weather outside... I'll look at those testers you mentioned.
I measured again with obd scanner, Icar, Ox sensors disconnected.
Results: Bank A Ox 316.25V varies. Bank B 229.90V varies. Ox heater 15.06 Ox sensor heater 46592%.
Ox sensor configuration, No Sure. Idle reference speed 48130. Ox sensor open circuit has been added to the fault codes, which is true, they are disconnected in this test. Bank A and B values are the same whether the Ox sensors are connected or not. Conclusion: Ox circuits are open in the sensors. The heating used to be low resistance, now it is open, so its detection by the ECM exists. Well, the car hasn't been used for 10 years at the mercy of the weather outside... I'll look at those testers you mentioned.
Datatek
Well-Known Member
Sorry but to me all those voltages are nonsense as is the % figure. how in a 12 volt system are you going to get 316.25 volts?
So, those volts are not really there, I suspect that the ECM has failed and is running some maximum values for some reason, which I am not the right person to answer. This is so utopian, but I get these values now, every time. The obd tester doesn't see such volts, apparently it just tells what the ECM circuit shows. and which is not true. It might be possible for me to borrow a Nanocom later this evening when my friend returns home. Let's see then.... Those testers you mentioned don't exist in Finland, maybe similar ones do.
If you mean the volts given by Bank A and B, I haven't tried to measure those volts in any way. I think that these wild volts should be interpreted as a destroyed part inside some bigger microcircuit, and then you get an incorrect reading.
I am even more convinced, the ECM declares itself thus destroyed. When there was no warning light or sign of this fault except for a slightly vibrating idle, it just occurred to me how many others have the same symptoms. The car also passed the emissions test during the inspection. with the same Ox sensors.
I am even more convinced, the ECM declares itself thus destroyed. When there was no warning light or sign of this fault except for a slightly vibrating idle, it just occurred to me how many others have the same symptoms. The car also passed the emissions test during the inspection. with the same Ox sensors.
Could you just measure those A or B banks, eg C507, pins 33 and 32, is there positive or negative voltage if you measure the Plus or ground terminal with a Fluke 365. I also have a UNI-T UT81B scope if needed. You cannot connect the meter to all pins, you have to be careful.
Yes why not.
* The left & right O2 heater circuits should have 12V on one side, and the return to pin-21 (pre-cat) & pin-28 (post cat).
* The actual sensor side will need an oscilloscope scope or very-fast digital meter to see the switching. The voltage will toggle every 1-2 seconds at idle, and faster as the engine revs up.
The best way would be to buy a cheap Bluetooth OBD (£20 on amazon) and do what I posted above in #91 above. Those blue waveforms are live readings from my GEMS P38 on a short drive this morning.
Any recent OBD reader with Live Data should work on the GEMS.
* The left & right O2 heater circuits should have 12V on one side, and the return to pin-21 (pre-cat) & pin-28 (post cat).
* The actual sensor side will need an oscilloscope scope or very-fast digital meter to see the switching. The voltage will toggle every 1-2 seconds at idle, and faster as the engine revs up.
The best way would be to buy a cheap Bluetooth OBD (£20 on amazon) and do what I posted above in #91 above. Those blue waveforms are live readings from my GEMS P38 on a short drive this morning.
Any recent OBD reader with Live Data should work on the GEMS.
