I have a 2010 R56 S that I rebuilt due to skipped timing. She has been running well except a 2ee5 MAP thermostat activation issue. I have swapped out thermostat housings from Stant x 2, a Mahle, and 2 OE Mini housings and the code persists. This did not occur before the rebuild. I have checked for continuity from the sensor plug to terminals 17 and 49 of the DME and the wires are intact. Anything else I should try before I swap out the DME?

 

Check the connections on the thermostat housing and make sure the plugs aren't crossed.

 

Nothing to get mixed up. Single wire goes to oil sensor, one with two wires goes to coolant sensor up top. Only one sensor to MAP portion of the housing.

 

If the DME fails to supply voltage and/or ground at the DME MAP thermostat pins, then the DME is faulty.

 

Any way to test the DME at the 17 and 49 pins?

 

Backprobe the connector pins. You should use backprobe adapters for your multimeter to avoid damaging the wires and connector pins.

 

I've looked online and can't find any listed voltage values or testing conditions in which to gather data. Any insight into this?

 

The video above may have the answers you seek about voltage (seems to be 12V) and conditions (turning on heater) as is done to bleed air from cooling system. Also see video comments section.

To verify that the heater element is good, do an Ohm test across the two MAP thermostat pins. The reading should be about 15 Ohms.

 

https://www.northamericanmotoring.co...ml#post4614963

^In this 2022 post, member mkov608 speculates that the DME may supply 5V to the MAP thermostat, though this was not verified in the thread. He also proposes conditions for monitoring voltage readings for the heater element over time.

 

I'm familiar with the video. I'm not asking about voltage, but how I can turn on the circuit to be able to determine if the DME is able to properly send power or ground to the housing. What I've come across on a Gates website is that activating the sport mode may activate the MAP circuit.

 

This is a good post. My connector only has two pins. Will give this a try and report back.

 

Follow-up:
New OE MINI thermostat housing resistance 13 ohms

Red lead in pin 1, black lead in pin 2 of the MAP connector:
Key out basically no voltage
Key in 3.2 V
Key in and start button pressed (engine off): -8.2V
Engine on -10.7 V
Engine at 221 degrees F: -10.7
Engine off, key out: 3.2V->.4mV after one minute
Unlock door: 3.2V

 

2010 N14, right? If so, your MAP thermostat should have an orange (OR) wire and a white (WS) wire.

 

Correct, but funny thing is the car was manufactured 05/2010 and the connector only has two pins unlike your wiring diagram. My Bentley has a slightly different diagram from yours. What is the source for yours?

 

Based on the circuit diagram, pin 1 (orange wire) is DME power and pin 2 (white wire) is DME ground.

What's odd to me is your detection of expected voltage polarity (+V) with key-in but unexpected reverse voltage polarity (-V) with key in+start or engine on. These observations make me lean toward a diagnosis of bad DME. However, I highly recommend you send mkov608 a private message with a link to this thread to ask him for his professional assessment.

 

I found it strange as well that is why I included the polarity. I PMed mkov608.

 

Maybe, Maybe not is correct; his schematic is accurate for your vehicle. I pulled up your car via the VIN in Mitchell. Mitchell doesn't state if the wires back at the DME are power or ground, but the previously uploaded schematic points that out as power flows from the to top of the schematic (DME) down to the sensor and then to the ground.

I do not see how the DME would suddenly reverse polarity coming out of pins 17 & 29. If it did you would have multiple other faults since the power for the map thermostat is shared by the turbo charger coolant pump, volume control valve, the downstream O2 sensor, and the upstream O2 sensor (all orange wires). It's more likely that you had your multimeter leads reversed, or there is a problem with the multimeter.

With the schematic provided by Maybe, Maybe Not, this is a ground-side, pulse width modulated circuit. To determine if the circuit and the DME are functioning properly, you need to connect a lab scope to pin to on the sensor with it connect and monitor the square-wave signal. If you don't see a square wave signal, you have one of three problems, (1) the stat is bad (not likely since you've changed them multiple times, (2), you don't have continuity in the power or ground circuit (orange or white wires), or the DME is not providing the specified voltage on the orange wire. Remember, this circuit may only be active when the engine is running. I'd start the engine and disconnect the connector from the thermostat; black wire on the multi meter to the battery negative terminal, and the red multimeter lead to the orange wire (don't damage the connector when you check it. I'll run out and check the voltage on my car since I don't know if it's a 5 volt or a 12 volt circuit.

 

The reading as posted above were check and were repeatable. I've check continuity of the orange and white wires and they are intact (pins 17 and 49)

Following your directions: Connector taken off from the housing and red lead in pin 1 of the connector and black lead on negative battery terminal.
Key in -237 mV
Start button pushed/engine off -12.6V
Engine on -14.0V
Weird

 

I just went out and checked the MAP Thermostat on my '09 Justa.

1. Voltage on the orange wire it system voltage ... whatever the battery or alternator output is.
2. There is no activity on the circuit on a cold engine; activity doesn't start until the coolant temp reaches 221 deg F.

You should see a wave form similar to this on the white wire.



Once you reach operating temp, the DME will start to pulse width modulate the circuit; the wave form will start to look like this.

 

upload a pic of your multimeter where the leads connect.

 

What are the max and min voltages of the waveform pulses?

 

Scope was on a 10 volt scale, so each horizontal bar represents 10 volts. Min would be zero, and max will be system voltage.

 

That was the issue with the polarity. I don't have a scope.

 

Do you have a test light?

 

I assume you are saying that the pulses are 0V min to 10V max.

10V is not too far from RUPNOK's 10.7V at the backprobed MAP thermostat connector with engine running and fully warmed up, so maybe the MAP thermostat is working?