AEM and AEM Gauge-Type WB02 Sensor Grounding

[HydeDW]

For the AEM users; Which grounding method have you used for the Gauge-Type UEGO Controller?
A. Ground to Chassis
B. Ground to AEM pin 72 (for 91-93 years) or pin 92 (for 94-97 years)?

I chose B. Are there any known issues doing this?

Dan
97VR4

[Austin@STM]

Ground is ground, for the most part all the ground wires connect to each other, and they all end up on the frame at some point. For guages i generally just ground it right to the frame wherever the closest spot is.

-Austin@STM

[HydeDW]

Ground is ground, for the most part all the ground wires connect to each other, and they all end up on the frame at some point. For guages i generally just ground it right to the frame wherever the closest spot is.

-Austin@STM

Thanks - but...
Ground wiring capacity(size/gage/resistance) must be sufficient to handle a given amp load. The AEM GAUGE TYPE UEGO supply current is identified at 1.3 amps .. and I have two. Plus all other sensors ground there - IAT, MAP, EGT(x2).
The reason that drove me to the AEM pin is that it is a (or the) reference ground internally for the ECM so sensor input readings remain accurate even with change in battery/supply voltage.

The UEGO (I presume) draws a greater load than all other sensors as it has a guage display and micro electronics and O2 heaters to power. Concerned about that.

Dan
97VR4

[Austin@STM]

I would just go to chassis ground, that is how we have done all of our cars for years now and they all work great. I agree with the comment about wire capacity, if you run to much you can fry a wire, thats why i wouldnt hook it up to the ECU, if something goes wrong you might take that out to.

Also, what is the reason for running 2 UEGO's

[HydeDW]

I would just go to chassis ground, that is how we have done all of our cars for years now and they all work great. I agree with the comment about wire capacity, if you run to much you can fry a wire, thats why i wouldnt hook it up to the ECU, if something goes wrong you might take that out to.

Also, what is the reason for running 2 UEGO's


Two provide sensor feedback and control for left & right bank and some visual behavior feedback in cabin; mounted in triple cluster with Defi Fuel Pressure.

I may revise/augment the current grounding connection method to Chassis for those O2 sensors. By "augment', a thought is to run separate ground lead of heavier gage straight from Battery just to the UEGO's to supplement but still leave connection to (in my case) PIN 92. Current will flow for the O2's should then flow to the ground of least resistance; a heavier gage.

However, after some study of the stock wiring diagrams just now, I note that all 4 of the narrow band heated O2 sensors are grounded at PIN 92. Makes me think now I may be concerned about nothing!

Dan
97VR4
ed

[steve]

You don't want to hook up the UEGO's power ground to the ECU's sensor ground, use the ECU pins 13/26 or directly to a good chassis ground.
If it had a separate ground to go with the Analog output I'd run that to sensor ground.

[HydeDW]

You don't want to hook up the UEGO's power ground to the ECU's sensor ground, use the ECU pins 13/26 or directly to a good chassis ground.
If it had a separate ground to go with the Analog output I'd run that to sensor ground.

Yes.. I see PIN 26 is where the ECU itself is gaining it's ground - an INPUT. With the new information (for me at least) about how the ECU grounds the stock narrow band sensors (I have none anymore), does that alter your assertion any about not using PIN 92?

I wonder just how many amps can be carried by a 1.5mm (.059") wire size - that is PIN 92 according to the shop manual. I need to go research.

Thanks
Dan
97VR4

[cjbyron]

Certain components are more susceptible to stray interference than others. Such interference can be introduced from using a chassis ground. IIRC the AEM (and some other brands too) UEGO specifically mentions in the install instructions to NOT use chassis ground for that very reason. If concerns are just amperage, run a line direct to the battery -.

[steve]

Yes.. I see PIN 26 is where the ECU itself is gaining it's ground - an INPUT.

Pin 13/and 26 are not inputs unless you know enough about electronics to know the current flows from ground to the more positive points. They are the chassis ground connections for the ECU. Pins 72 (1G) or pin 92 (2G) are the sensor ground for the noise sensitive analog inputs to the ECU. If the UEGO had provided a separate ground lead for it's analog output I'd connect that to one of those pins but since the AEM manual I'm looking at (30-4100 Installation Instructions) doesn't and says the black wire should go to a clean power ground I'd use either pins 13/26 or a solid chassis ground.

I don't see the reference cjbyron is talking about but it's likely a different manual.

Some of the other AEM UEGO controllers have a signal ground (brown wire) that one should go to the sensor ground if it's present. One example is the AEM UEGO inline controller.

The factory O2 sensors don't generate much current and are very easily effected by stray noise. You'll note that they and the shield on their cable are connected to the sensor ground.

[HydeDW]

Pin 13/and 26 are not inputs unless you know enough about electronics to know the current flows from ground to the more positive points. They are the chassis ground connections for the ECU. [snip]

The designation of INPUT for the pin 26 (verses OUTPUT) is from the AEM EMS P/N 30-1311 installation instructions (the table column "I/O"). I can't say I understand why they designate all the ground pins as INPUT except for Pins 72 (1G), pin 92 (2G) which is designated as OUTPUT.

Good info - thanks.

Dan
97VR4