question: coolant exit is -48 in INPA, DME going bad?

[PowerSax]

Good Day. I've searched and searched. Been trying to fix this for a couple weeks actually.
If this is in the wrong section, please move it or tell me where to put it (lol).

Motor is a 2006 S54. Car is a 1998 318ti. I know, not an e46 but the motor thinks it is. I used the e46 radiator, sensors, DME, etc. I am asking here as this site is so knowledgeable on the inner workings of the DME.

The question. I had to reset the DME for various parameters because of the swap. Is there any chance I turned off the auxiliary fan somehow? If so, where do I start, fresh bin dump from github? Full or partial? Or is it time for a new DME?

A long diatribe on what I have done to date.

This stated with my aux fan not kicking in. Read the e46 fan guide (thanks), tried all the trouble shooting to include leaving the sensor unplugged. No fan. Tried to control the Aux fan in INPA. No worky. Looked in INPA, and the coolant exit reads -48.
Figured I need to fix this first. Bought a new Hella sensor for the lower radiator. Same, no reading. Checked the new and original sensors with ice / hot water and they both responded with readings of 500 - 1800 ohms. Checked the wires for continuity from sensor to the DME and got .9 ohms from both with no shorts to the other or to ground. I plugged the sensor back in and checked the readings at the DME side wires. Pins 38 &39. It seems to have ohm'd out fine. 70*f it was just over 1000 ohms. I was wiggling all ends of the wires with the meter connected. It did not change, so I am pretty sure there is no shorts on any of the wires. put it all back together, and I am getting 5v from the DME pin 39. This also seems fine.
I also checked the aux fan connection and get 12v between the 2 thick wires. Read it is hard to read the PWM wire without a scope.
Now you're all caught up.

[sapote]

1. Tried to control the Aux fan in INPA. No worky.
2. Looked in INPA, and the coolant exit reads -48. Bought a new Hella sensor for the lower radiator. Same. Checked both sensors with ice / hot water and they both responded with readings of 500 - 1800.
3. Checked the wires for continuity from sensor to the DME and got .9 from both with no shorts to the other or to ground. I have hooked the sensor back up and checked the readings at the DME side. Pins 38 &39. At 70f it was just over 1000.
4. I was wiggling all ends of the wires with the meter connected. No change.
5 Hooked it all back up, and I am getting 5v from the DME pin 39.
6. I also checked the aux fan connection and get 12v between the 2 thick wires. Read it is hard to read the PWM wire without a scope.
Now for the question. I had to reset the DME for various parameters because of the swap. Any chance I turned off the Auxiliary fan somehow? If so, where do I start, fresh bin dump from github? Full or partial? Or is it time for a new DME?

1. how do you know if the fan is good or not?
2. "Both sensors responded with 500 - 1800". is it in F deg or measured in Ohms? I don't understand why such a wide variation range on the reading. Be clear as we can't read your mind.
3. "At 70f it was just over 1000." Again, in deg F or Ohms? I don't like to ask for confirmation on this.
4. Assuming 1000 means 1000 ohms. What value do you expect to see?
5. I'm not surprised to see a reference of 5v on pin39 as the DME circuit needs to send a bias current to the sensor (just a variable resistance material) in order to measure its resistance (then convert to temperature).
6. Nowhere did you say the fan module is known to work or not, then who cares what the pwm signal looks like.

[PowerSax]

Thanks for the help sapote. Really appreciate you taking your time.
I try to read these back several times before posting it so it sounds clear, but sometimes it's the simple things.

1. I do not know if the fan (box) is good or not. That was just how this whole ordeal started. I did replace it with an (unknown good) 330i one. Honestly, more worried about my DME, then will work on the fan. I do have my eye on a couple of Mazda 3 (Bosch) controllers on eBay.
2. This reading is Ohms. Both units were off the vehicle for testing first in a cup ice water and then a cup of not boiling hot water. In Ohms, this reading does not seem out of range from what I have read.
3 & 4. This was 70*f reading 1000ish Ohms. From what I have read, this seems to be around the range one would expect. So sorry I missed all the nomenclature. I really was trying to put as much info as I could, mostly so people could see where I have been.
5. I knew it was supposed to have 5v dc. By this point it was all back together. I read that sometimes the DME becomes corroded and won't output 5v dc. I did not take the DME apart. Trying to trouble shoot still.
6. This was added because if I could see what my PWM signal is, then I would know if my fan and or controller box is bad. I am not getting errors for the aux fan (even though it never kicks on). My concern at the moment is the -48* reading in INPA for the lower radiator sensor. Am I overthinking and should just throw another fan at it?
I did have the z4 fan settings from the ECU werks (sic) binary tool. I changed it back last night. No change to the sensor reading or the fan operation.

I rearranged the original post. Hopefully it is easier to read.

And, thanks again sapote

[sapote]

1. I do not know if the fan (box) is good or not.
2. Looked in INPA, and the coolant exit reads -48.
3. put it all back together, and I am getting 5v from the DME pin 39. This also seems fine.

1. Does car have a working AC? Turning on AC should force the efan to run regardless the radiator outlet sensor.
2. -48F means the DME sees the temp sensor as an opened circuit (these sensors are Negative temperature coefficient so -48F coresponding to a very high resistance or infinity)
3. The DME circuit typically sends a current through the sensor (a variable resistor) and through a reference resistor. This means there is a voltage drop across the sensor. Can you measure this voltage? If the sensor voltage is zero, then it means the circuit is open, bad.

As about 500 - 1800 ohms, they are coresponding to measured vallues at hot and cold water and not the otherway around?

[PowerSax]

Thanks again for the time. No AC yet. It is low on my priority. Getting it running solidly is me main objective. I will check the rest out tonight. Had a fellow employee catch covid, so I am pulling doubles.
I sure will measure voltage at the backside of the sensor. I have to reassemble the car a bit. I'm sure you know the e36 has the DME in a little cubby, and the compact (ti) has the battery in front of that. I didn't put it totally back together this time in case I have to fiddle with the DME internals. I will also check the resistance measurements again as well as one more scan for codes with INPA.
Really do appreciate the little nits you are helping me with. This site is great!

[George Hill]

I don't think I've ever seen a DME fail and read the rad outlet temp sensor incorrectly. With it being -48F I would assume the circuit is open.

Is the pin(s) on the DME damaged?

I'd pop the cover off and see if there is any physical damage to the DME.

With the cover off you can plug the DME into the harness and measure the continuity from the backside of the header block to the temp sensor with everything connected. Should isolate whether its a wiring/sensor issue or not.

[PowerSax]

Thanks GH.
I am always open for more things to try. I did look at the two pins last time it was apart, and they were in place and not corroded. I will read through from the backside as you stated.
I did not think it was the DME as it all worked fine in my e46 before I pulled the engine. That is why I asked if I may have coded that part of the aux fan out when I was doing all the XDF's and / or using MSS5* binary Modification tool.

Those 2 wires are in the swap harness, but I have tested them for continuity like 5 different ways now. Checked for voltage on one side, but I will do a couple more variations.
Thanks again all, I'll take these suggestion for any / all the tests to heart.

[George Hill]

I misunderstood. You programmed the DME yourself? Can you just revert it back to stock to verify the rad outlet temp is reading correctly?

[bigjae46]

Thanks GH.
I am always open for more things to try. I did look at the two pins last time it was apart, and they were in place and not corroded. I will read through from the backside as you stated.
I did not think it was the DME as it all worked fine in my e46 before I pulled the engine. That is why I asked if I may have coded that part of the aux fan out when I was doing all the XDF's and / or using MSS5* binary Modification tool.

Those 2 wires are in the swap harness, but I have tested them for continuity like 5 different ways now. Checked for voltage on one side, but I will do a couple more variations.
Thanks again all, I'll take these suggestion for any / all the tests to heart.

Check the resistance of the wires as well. That will detect a bad wire which will be a more common issue as these cars get older.

[PowerSax]

The DME circuit typically sends a current through the sensor (a variable resistor) and through a reference resistor. This means there is a voltage drop across the sensor. Can you measure this voltage? If the sensor voltage is zero, then it means the circuit is open, bad.

With the cover off you can plug the DME into the harness and measure the continuity from the backside of the header block to the temp sensor.

Thanks. I had a little time between double shifts and got to try these.
The DME looks spotless inside. Surprised me there is no sealant. Assume for cooling purposes. Continuity right through thse teeny tiny pins. Put it all back together and check voltage at the backside of the sensor plug, nada. Second sensor is bad. And it was a Hella.
Ordered a new OEM and am awaiting shipment.
Also, the voltage at the sensor plug hot side dropped from 5v to 3.3v when I offered the sensor up.

I can’t thank all of you enough for helping others. The knowledge here is crazy great.

I guess my lesson is don’t get hung up on “new is good”. I will add updates on this and the fan action.

[sapote]

1. Put it all back together and check voltage at the backside of the sensor plug, nada. Second sensor is bad. And it was a Hella.
Ordered a new OEM and am awaiting shipment.
2. Also, the voltage at the sensor plug hot side dropped from 5v to 3.3v when I offered the sensor up..

1. If no voltage at the sensor 2 pins then either the wires from DME are bad open, or the sensor is shorted internal with 0ohm and zero volt drop.
2. This sensor caused the 5v opened connector changed to 3.3v when plug in. But of sensor in (1) had no voltage then why sensor in (2) had 3.3v? Is it a new sensor (but you're waiting for shipping)?

[PowerSax]

Thanks for the patience sapote. I must be getting you so sore at me.

I will start at the top. Post number 4:

"As about 500 - 1800 ohms, they are corresponding to measured values at hot and cold water and not the other way around?"

The colder the sensor gets, the higher the ohms go.
I tested it with the original sensor that came with my motor, and the one I had ordered and received earlier. It was a Hella. They both tested the same as far as the hot and cold ohms.. I have since placed an order for another sensor. It is OEM. That is the one I am awaiting now. This partially answers point #2 below.

From post #10

1. If no voltage at the sensor 2 pins then either the wires from DME are bad open, or the sensor is shorted internal with 0ohm and zero volt drop.

I was at work on my iPhone. Again, thanks for the patience and the knowledge. I will clarify.
These all relate to testing of the sensor side wiring. With no sensor offered up, I get 5v at pin 1, no volts at pin 2. With the sensor installed, pin 1 changes to 3.3v, and pin 2 reads 0.2v. I called that 0v earlier, but maybe 0.2 makes a difference.

2. This sensor caused the 5v opened connector changed to 3.3v when plug in. But of sensor in (1) had no voltage then why sensor in (2) had 3.3v? Is it a new sensor (but you're waiting for shipping)?

Hopefully this was answered by the two replies above.

You said "...then either the wires from DME are bad open, or the sensor is shorted internal with 0ohm, and zero volt drop". If I am understanding this right, an internally shorted sensor will read 0 ohms, and not change with the temperature. Correct?

I am 95% certain the wires are not shorted. I have tested them out to 0.9kohm from one end of the wire to the other. This involved some vigorous movement of the wires on my part. No change on the meter, 0.9ohm. And (per George's suggestion with the DME open) from the teeny tiny pins on the board to the sensor side wire with dang near the same readings.

[PowerSax]

,,,You programmed the DME yourself? Can you just revert it back to stock to verify the rad outlet temp is reading correctly?

I did do some reprogramming of the DME myself. I used ECUworx binary modification tool in preparation for the swap. I changed the SMG to Manual and deleted the need for the EWS. This was back in January, and the motor/DME/etc were still in my vert.
A couple months ago I used tunerpro with the XDFs from saildot4k to change more swap items. This was to prevent trouble codes.
I was thinking I may have caused this, which is why I brought it up. Two possibilities, I could revert back to the stock tune. I did save it. As an alternative, I could instead use the binary readings (again posted by saildot4k) for a manual US spec car. That is after I rule out this dang sensor. At least I know the DME looks good, at least to my eye.

Thanks again for the help/suggestions.