MBE 9A4 oil temperature sender connection

[Hanns Per]

I connected an oil temperature sender (same sensor as the water temp sensor) to the MBE 9A4.

The water temp sensor is connected to Pin 2 (signal) and Pin 5 (sensor return). Several sensors are connected to Pin 5.

For the oil temp sensor I used Pin 19 (signal) and Pin 5 sensor return.

Voltage reading are the same for water temp and oil temp. I calibrated the oil temp the same as the water temp. In easimap Oil temperature is put on Pin 19.

However I cannot get a value shown in easyimap 6.

There are more setting in Easimap for water tep sensor than there are in Oil temperature.

Does anyone know if it is possible to get a reading the way I connected the oil temp sensor at all? and in case How?

Thank You Hanns Per

 

 

[aerobod - near CYYC]

In the chipfile you have loaded to the 9A4, I'm assuming you have done the following:

Under "Maps and Settings" / "Programmable Pins"

"Use Programmble Pins" = Programmable Pins Enabled

"Oil Temp Input Source" = Pin 19 (or Pin 19 Inverted)

After the chipfile is written to the 9A4, the 12V supply to the 9A4 has then to be cycled for any pin configuration settings to take effect.

[Hanns Per]

Thank You, now i get a reading on the oil temp.

But water has 3.87 volt with the correct temp  and oil shows 0,16 volt. does it relate to inverted? I could not select in programmable pins > oil temp source "Pin 19 inverted"

or is it a matter of calibration?

Or should I connect the wires the other way round?

or what does it mean the 12V supply to the 9A4 has to be cycled ( english is not my native language)

Thank You again Hanns Per

 

 

[aerobod - near CYYC]

With a normal sensor, reversing the wires won't have any effect, it is just a temperature sensitive resistor. The pin reversal in the ECU would be necessary if the resistance changes in the wrong direction relative to the temperature. This is what my Easimap version (Easimap 6 r50, chipfile software version 9A4be621) shows for the programmable pins:

Cycling the 12V supply on the ECU requires disconnecting the battery for a short period (20 seconds should be enough) so that the ECU completely powers down and is then rebooted.

If your wiring earths are all good I would say that calibration is what is required. If possible I would remove the sensor and place in a small bowl of water that has been heated to a know temperature while the sensor is still connected to the ECU, then record the voltage shown in Easimap for each different temperature of the water. If you can't test the temperature in a water bowl, then an infrared/laser thermometer can be used as the engine warms up to check the temperature of the body of the sensor and record the corresponding voltage.

(PS your English is much better than my German could ever be!).

[Hanns Per]

Thank You again,

checked again and the voltage reading is =.10 volts for the oil and 4 volts for the water. When i heat up the oil sensor it goes don to 0.09 and so on. (i.e. in the wrong direction.

Would this be different when I choose Pin 19 inverted?

However in my version I have no inverted possibility. If I read correct my MBE is a 9A4be400 version

thanks again Hanns Per

PS: calibrating would be no problem for me

 

 

[aerobod - near CYYC]

The voltage and resistance should drop as the temperature increases for the normal Bosch type sensor that MBE/SBD tend to recommend, here is a calibration curve that you could use to compare the resistance of both your water and oil sensors to: Bosch Temp Sensor Spec

The inverted pins config allows the voltage to change in the opposite direction, but calibration that maps decreasing voltage to increasing temp can also work. You can update your ECU firmware version (my 9A4be621 version is from 2015) by downloading software from the SBD website, it looks as though 9A4be871 is the latest release from the their site. I would follow their instructions very carefully, if you do upgrade, but I have done this twice on my ECU so far.

With the low voltage reading you are seeing I would say that the sensor is either mis-matched with a too-low resistance, the sensor is faulty, there is a pull-up resistor somewhere in the circuit that may not have the right value, or there is a problem with the wiring (such as a high resistance earth).

[Hanns Per]

Good Morning,

upgraded to R63 and 871 and can choose now Pin19 and Pin19inverted. checked sensors they are both OK. When I measure the Voltage in the plugs without sensor they both show something like 4.85 Volt. This is also seen in Easymap.

However when I plug in the sensors  the Water sensor reading is something like 4.85 (its cold in the garage) and the oil is something like 0.15 or 4.85 (inverted).

Water signal in Easymap is between 5.0 and 0.0 Volt depending on temp. but oil only between 0.15 and 0.0 Volt or 4.85 and 5.0 Volt.

I could not find any parameters  where I could set this correct?

Thanks again Hanns Per

[aerobod - near CYYC]

I would remove the connectors from the sensors and measure their resistance when they are both at the same temperature. if you haven't already done so. If the Bosch type of sensor they should both give a resistance that that is in the range of 2000 to 5000 ohms in the 10 to 20C range.

If that seems correct, I would then remove the connector to the 9A4 and measure the resistance from each pin to the sensor connector end (oil sensor +ve to pin 19, oil sensor -ve to pin 5, water temp +ve to pin 2). The resistance should be 0.5 ohms or less in each case. I would say If higher than 1 ohm, you will need to trace the wiring to resolve the problem.

Although the sensor shouldn't be directional from a connection perspective, if it is marked with a + or -, make sure pin 19 goes to the +, just in case the manufacturer has added a diode for one reason or another.

[Hanns Per]

Thank you once again

I switched the sensors and in the water connector both sensors show the same and correct voltage ind in the oil connector (on 19 the value between approx. 0.15 Volt and when warmed up less than 0.15.

Measured the sensors ohm both within the range 2500 and 2800.

measured the ohm of the lines from the 9A4 connector to both sensor connectors all within 0.6-0.8 ohm.

No marking on the sensors, they are both the sae  Bosch sensors.

I think it has something to do with the parameter settings of the oil temp sensor in the MBE?

 

 

[aerobod - near CYYC]

To calibrate the sensor in Easimap, under "Sensors" / "Oil Temperature" / "Oil Temperature Sensor Limits & Defaults", you should be able to adjust the oil temperature calibration curve for voltage vs temperature.

From what I can tell for the water temperature sensor (which has more configuration options than for the oil temp sensor), depending on the settings a 1K ohm pull-up resistor can be added or removed, this doesn't seem to be an option for the oil temp sensor. To get the voltage in a usable range you may need to add a pull-up resistor before calibrating the sensor. You would normally add a resistor with a value about equivalent to the resistance of the sensor at normal operating temperature, which would likely be between 100 and 500 ohms. I would start with 500 ohms and connect it between the 5V reference (pin 4 or 22) and pin 19. It may be possible to test the correct resistor by carefully inserting it into the back of the ECU connector to touch those pins, but be careful not to damage the connector or the wiring. A lower risk test solution could be to find a 5V power supply and connect +5V to the pull-up resistor, the other end of the resistor to the oil temp sensor pin that is connected to pin 19 on the ECU and the power supply 0V to the oil temp sensor pin connected to pin 5 of the ECU.

If the pull-up resistor test works, then splicing in the resistor into the existing wires or re-pinning the 9A4 plug would be needed (this will require pins obtainable from SBD, plus the correct crimping tool).

[Hanns Per]

Thanks a lot,  now it works.

I finally used a 1k ohm resistor which gave me exactly the same voltage reading as the water temp sensor at the given temp. with the same calibration as the water I use now 19 and not 19inverted.

Thks. a lot Hanns Per

 

[aerobod - near CYYC]

Glad that it is all working for you now Hanns.