Hi all. Been working to update our CAN-2-CAN gateways by covering some additional E38 and E67 gauge parameters. Most recently ask about adding engine oil temp, IAT or IAT2 options to the NMEA and J1939 available translation list for guys swapping into boats.

So last week I grabbed an E38 off a 2011 5.3 truck to verify some additional Dynamic PID's. That's when I discovered while PID's for things like EOT or IAT2 are valid, it depended on chassis wiring and OS version whether they actually report true values. Found the write up on repining IAT from MAF to main intake sensor where IAT2 isn't available on E38 variants. That's easy enough. But what I can't seem to find is how the ECM gets a [TRUE] EOT signal. Is there a write up on this mod anywhere??


According to one document I found, engine oil temp signal was on connector X2 pin 23. But another 08 LS3 pinout I found shows either "unused" on the automatic, or "Transmission Fluid Temperature (TFT) Sensor Signal" for manuals. But no E38 EOT pin listed on any ECM pinouts. From the oil pan sensor, Circuit #357 -- Oil Temperature Sensor Signal -- shows it going to IC.

So today I upgraded the 2011 truck ECM to an 09 LS3 manual OS 12628990. That change activated X2 pin 23, and now reports correct TFT sensor signal PID data. Still not was I was looking for... Cause in the LS3 tune file {G1218}, there is an option to run an actual EOT SENSOR. See attached.

What am I missing here? I understand EOT was a "Calculated" value from factory, but sure looks like it can be brought into the ECM a couple diff ways. Gotta be ECM pin associated.

For marine swaps or others where an aftermarket cooler is being used, getting the ECM to read true oil temps is far more useful for fueling control.

Thanks

-K

 

150 views and not a single reply??

Ok kiddies I'll break it down for ya in detail soon as I verify the options over a few OS versions. But in short, the 08-09 LS3 Vette OS doesn't use the EOT sensor in pan for anything more than values shown on HUD best I can tell. It has no physical connection to the ECM. The ECM ALWAYS calculates the EOT value, and related tables use that calculation. What your see on a scan tool is only a calculation. So if you put a aftermarket oil cooler, or say drop it in a boat with seawater cooler, your getting false data..

What does use the oil pan level/temp sensor is 2009 G8 LS3 OS, and the 2010 Camaro L99 or LS3 with MYC transmission only. I'm still hacking around on it, and will verify the pin signal matches CANbus value out before conclusion. But be aware that just because you see a oil temp value on OBD-II data, doesn't mean it's actual...

 

Ok here is how to get actual Engine Oil Temp values into E38 hardware.

First, this mod requires a cax file, or some manual bin file editing to change pin 23 assignment. For that reason, I was only able to test this mod on two OS versions below. I'll share a link to the cax files used, but hopefully it makes an upcoming release of EFIlive.

2009 LS3 OS 12628990
2006 LSx OS 12639835
2007 LS7 OS 12614676

In a normal setup, depending on chassis and OS, the X2 pin-23 is used for transmission temperature input. Or is unused.

I tested this on the bench by hooking up a POTs between low reference line and pin 23. With no other sensor signals connected, and using a couple different diagnostic tools, verified pin 23 is a truly Trans Temp input as listed in most docs.

Second, I changed the value in table {G1218} from [Calculated] to [Sensor]. No change in the pin assignment, or calculated values received by OBD-II Mode 1 pid 0x5c. Engine Oil Temp.

With a little help from the EFIlive crew, I came up with a address for the pin assignment. Sure enough, there was an option to assign it to EOT or Trans Temp. Here is link.

Created a cax file for each OS and dropped them in the correct directory. Opened a tune file and set the pin value to "0". This in tern changes the pin assignment to EOT from transmission temperature. See pics below.

Several tables can use EOT to limit RPM based on oil temps. These tables are:

{B5212} Rev Limiter By Oil Temp
{B5213} Rev Limiter By Oil Temp Enable RPM
{B5214} Rev Limiter By Oil Temp Disable RPM

After some further testing, the standard EOT reading in OBD-II tools such as Torque, still shows "Estimated" temps and not true. To verify this, I hooked up ECT and IAT sensor to a POT's and powered up the ECM. The estimated EOT value is directly linked to both those sensors at start up. I believe Load may also play into this estimate, because after intital key on, EOT doesn't track directly to ECT & IAT changes.

To read true oil temps after the pin mod is completed, you will need to use Mode 22 Pid 0x153e. I added this PID to torque, and posted a couple pics to show the actual differences. It should also be noted that Trans Temp now shows a 350F constant.

Next to test on running engines. If it all works as planned, the actual EOT values can now be displayed by aftermarket gauges. What shows on factory HUD is yet to be seen. But it should at least allow for an extra safety measure in tuned into stand alone applications using the tables above. I'll update when I get time to test it further.

Cheers,

-K

 

Forgot the link to cax files.. :-)

 

kidturbo, I found this information very helpful. Thanks very much for your efforts!

 

LOL - yes, because you're in WAY over the head of the average poster. But thanks for detail, following to learn a little something. I took the approach of simply adapting/installing all my old analog senders and using my stock analog gauges. But who knows, maybe someday the digital revolution will invade my dash!