E38 ECM questions
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On The Tree
Joined: Jul 2020
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E38 ECM questions i have a E38 ECM from a 2013 silverado. i have the OG harnesses and everything is stock. (it is a swap into 1986 C10) i am getting a high temp reading error at the ECT (water temp). i have checked the ECT and the harness from ECT to the ECM and the resistance (ohms) appear to be good. friends think it might be a "bad" ECM. i would like to know if there is a diagnostic (or something) that can be done to check if the ECM is correctly working or if it is not functioning correctly? also if i need to replace ECM is a refurbished unit ok? and what needs to be done to use the replacement (IE: programming and/or tunes)? overall the engine runs fine & is not hot. all other functions "appear" to be in good working condition (ECM wise).
thanks!
thanks!
Not a easy to bench test to see if it coolant temp is working correctly. We only sell used or new ecm's, we throw away remans one due to the numbers of issues we have seen. If you go used or new both options are going to have to be programmed for your swap and mods before it will run. We can clone your current ecm to another one if your happy the current tuning.
Thread Starter
On The Tree
Joined: Jul 2020
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minitrker, thanks for the reply. is it possible that the tuning could have "messed up" the ECM to cause the error with the ECT? can the tune have a "wrong" setting" related to the ECT reading? if i go with your suggestion (cloning) would you be able to give me a rough estimate of cost for procedure (pm if desired) also would the cloning procedure remedy the bad ECT reading at the PCM?
thanks again for time & effort.... much appreciated.
thanks again for time & effort.... much appreciated.
Tuning cant mess with the ETC readings...its bad sensor, bad wiring or bad ECM. It could just have a bad driver in ECM...I have seen ECM with no ETC and one with no MAP before, its rare but have seen those in person.
Thread Starter
On The Tree
Joined: Jul 2020
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thanks for the reply, minitrkr, I received the PM - thanks. I am going to dbl check my grounds to see if helps. the gauges are Dakota Digital VHX series with the BIM. all other readings appear to be in correct readings. I have setup the DD ECT sensor and harness to the box for the gauges and appears to be "more" accurate. i will also revisit the ohms (resistance) at the OG harness to PCM conn (J2 - pins 21 and 22)
thanks again
thanks again
Thread Starter
On The Tree
Joined: Jul 2020
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I think I have found what MIGHT be the issue. I did some reading testing this past weekend and found something. We let the engine run over 40 minutes and all the data was consistent with each other (except the ECM reading) all the data was indicating that the engine was running at around 220degrees on a consistent basis. The code reading was at a consistent 251-253degrees. The readings were not really affected by the AC on/off (vintage air sure fit system for the truck model) the only reading that was not similar was the ECM data. We did some internet research & it appears that GM issued a TSB related to some GenIV engines that had indicating running hot when actually were at the correct operating temps. The TSB addressed the ECM ECT sensor mapping, I believe it re-mapped the table to adjust readings related to the ohms.
My questions is can aftermarket tuning software (HP TUNERS or equivalent) make adjustments to the ECT temp table in the ECM? It looks like the table needs to be “shortened”/ adjusted to match the TSB GM table?
Also how would I be able to find the GM TSB information specifically the revised TSB ECT temp table? – if possible?Thanks!!
My questions is can aftermarket tuning software (HP TUNERS or equivalent) make adjustments to the ECT temp table in the ECM? It looks like the table needs to be “shortened”/ adjusted to match the TSB GM table?
Also how would I be able to find the GM TSB information specifically the revised TSB ECT temp table? – if possible?Thanks!!
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No there are no tables or settings to adjust the coolant temp sensor reading.....Im not saying its not impossible but I have tuned thousands of E38 vehicles and never came across one with an issue with the coolant temp reading off.
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On The Tree
Joined: Jul 2020
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minitrkr, thank you for your reply. I would like to get your opinion on what the issue could be as to why the physical engine and sensors all seem to read in normal operating range (not indicating hot), but the ECM is reading about 30degrees warmer (the degrees off is proportional to the warmer the reading - cooler=closer reading, hotter= further off) all indications show the engine is physically in normal range, but the ECM reading is hotter.
in general, I am under the impression that GM may have a TSB to recalibrate the ECM due to this reason, but I am not able/ know how to look for it.
finally can "MDI" software "Adjust" the ECT table in the ECM? if asking correctly.... LOL!!
THANK YOU for time on my questions, much appreciated
in general, I am under the impression that GM may have a TSB to recalibrate the ECM due to this reason, but I am not able/ know how to look for it.
finally can "MDI" software "Adjust" the ECT table in the ECM? if asking correctly.... LOL!!
THANK YOU for time on my questions, much appreciated
The TSB will be vehicle specific and you would need a VIN of one of the effected vehicles and then your ECM would have to be the correct service number for one of those. You would flash it with SPS with the VIN and updated calibration with SPS. Then read it out with HPT and re-license your ecm and re-do your tune. GM software and MDI does not allow you adjust anything, its all VIN based and a calibration off GM servers.
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Joined: Aug 2010
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From: Ann Arbor, MI
Compare your ECT sensor's ohm reading to the chart in this thread:
https://ls1tech.com/forums/pcm-diagn...0-f-284-f.html
I wondered about the effect of a corroded connection, but that would increase the ohms and reduce the temperature reading.
https://ls1tech.com/forums/pcm-diagn...0-f-284-f.html
I wondered about the effect of a corroded connection, but that would increase the ohms and reduce the temperature reading.
TECH Fanatic
Joined: Dec 2017
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From: Bossier City, Louisiana
My Dakota Digital HDX temperature sensor is on the passenger rear of the motor and my PCM engine coolant temperature sensor is on the driver's side front. And yes, my DD gauge is typically 20-25 degrees hotter than what the PCM is seeing. My vehicle would be exactly like your engine temperature situation if I swapped the installed locations of my temperature sensors.
Indeed, as measured with an infrared temperature gun, the back of my engine is hotter than the front by about that amount. Which makes sense - the back of the engine is further from the radiator and the rush of cooling air in general at the front of the vehicle.
I think everything is accurate for you. Stop worrying, I eventually stopped worrying. I even stopped worrying about how much difference in "hysteresis" there is between a GM temp sensor and that DD temp sensor. The GM temperature hardly moves at all once up to temperature (but does move somewhat) under any vehicle condition but the DD temperature gauge changes quite a lot with RPM and speed.
Rick
Indeed, as measured with an infrared temperature gun, the back of my engine is hotter than the front by about that amount. Which makes sense - the back of the engine is further from the radiator and the rush of cooling air in general at the front of the vehicle.
I think everything is accurate for you. Stop worrying, I eventually stopped worrying. I even stopped worrying about how much difference in "hysteresis" there is between a GM temp sensor and that DD temp sensor. The GM temperature hardly moves at all once up to temperature (but does move somewhat) under any vehicle condition but the DD temperature gauge changes quite a lot with RPM and speed.
Rick
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On The Tree
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Mrvedit, thanks for the reply. We used a similar chart but it indicated for later (gen IV) readings. I did see that thread and we compared them. The ohm readings against our chart also “checked” with the temps from the temp wire readings attached to the meters.
B52bombardier1, thank you for the reply and information. My sensor setup is the same… we just did not have the DD brain box connected. Between the wire heat temp. readings at the meters and the ohm readings at the meters, the physical engine was at operating temps (not above 220-ish) the ONLY indication that the engine was hot was from the code reader’s live data reading from the ECM information (OBD2 port).
I am not so worried about it now as previous, but I do concern if the ECM “thinks” the engine is always running at 250-ish will the ECM do something to prevent damage (IE: shut off or limp mode)? the IR therm. Readings also backed up the physical engine temps from thes ensors and various meters.
It was a funny setup… someone walking by would of thought we were doing open heart surgery with all the wire leads, meters, pointing of IR therm. And the running around doing the readings!
Thank you guys for replies, time & valuable knowledge. It is much appreciated.
minitrckr, I hope you don't mind .. I am sending a PM question. thanks!
B52bombardier1, thank you for the reply and information. My sensor setup is the same… we just did not have the DD brain box connected. Between the wire heat temp. readings at the meters and the ohm readings at the meters, the physical engine was at operating temps (not above 220-ish) the ONLY indication that the engine was hot was from the code reader’s live data reading from the ECM information (OBD2 port).
I am not so worried about it now as previous, but I do concern if the ECM “thinks” the engine is always running at 250-ish will the ECM do something to prevent damage (IE: shut off or limp mode)? the IR therm. Readings also backed up the physical engine temps from thes ensors and various meters.
It was a funny setup… someone walking by would of thought we were doing open heart surgery with all the wire leads, meters, pointing of IR therm. And the running around doing the readings!
Thank you guys for replies, time & valuable knowledge. It is much appreciated.
minitrckr, I hope you don't mind .. I am sending a PM question. thanks!