Motor temp Light

Hey man, you seem like the go to guys for this. I’m struggling to get rid of my temp light on my 2005 e4. I recently acquired the gem which has been sitting outdoors since 2007 or so. I did a lithium setup from Mike using bmw modules (24s). The car runs great aside from the lower speed. I have no wrench symbol when I key on and drive it. I attempted to unplug the motor temp sensor and jump the pins with no luck. I then measured voltage and have source voltage 86v at the connector on the grey/white wire coming from the power distribution module. When I measure voltage at the black/yellow wire coming out of the controller to the temp sensor I have 4v with the temp sensor unplugged. When I plug in the temp sensor and back probe at the controller I have 86v. I voltage drop tested both wires and I have no voltage drop. Resistance check I’m getting .1 ohms. I assume I need a controller unless there is something I am missing or if another circuit can affect this one. It’s strictly a motor temp sensor that the light is on for? Any help is appreciate man!

Not sure, but if it only goes to controller and it’s over 50 volts, sensor is ok.
I need to see how it’s wired. Does it affect performance?
Dead computer. No access to diagrams for a while.

I assume it’s affecting performance. I have a 96v setup with a magic magnet and still the 5hp motor and I’m getting 25-26 mph on GPS. I assume it should go faster than that.

The controller should not limit performance if pin 21 is high.
The only way the Gem psdm can cut back is putting controller in turf mode.
Make sure p4 is high and p6 is low. If p6 is high = turf.

When you said check that they are high and low what do you mean? I thought the power could be reduced since the motor temp warning is illuminated?

I see the diagram now. You want me to check for 72v on p4 or p6. I can tell you my switch indicator changes between high and low when I make the selection but I will check voltage at controller.

Two different things. I don’t know what illuminates the warning light. The controller can reduce power, but the only way it knows when is by the state of p21. It can’t read the state of the warning light.

The Gem psdm can control pins 4 and 6, independently of the switch setting. That’s why the wires from switch are routed through psdm.
Psdm monitors the battery level, and switches to turf mode if needed.
I don’t know from memory if the motor temp sensor goes through psdm or not. It must as communication is one way. The controller sends data p23 but does not have the rec. pin 22 connected.

Would like to make this public as it covers something new to me.

You can certainly make it public

I see the Motor Temp switch going to the controller (P21) as a BK/Y wire and not the PSDM. The motor harness plugs into the PSDM at J5. I’ll see if I can figure out what drives the lamp at the display.

@Turborobo - I’m guessing you have the MM and the VSpoof installed?
Just checking a few other things for clarity:
What trans ratio do you have?
What tire height are you running?
Does switching to DL(Turf) alter the performance at all?

Awaiting the results of what you find on P4 and P6. (maybe even remove the pin from the plug?)

I have a MM and

I have a MM and Voltage spoof. Unsure of trans ratio (I’m a newbie here. Untouched 2005 e4) 23” tall tire. I didn’t notice a difference when switching dh to dl but I didn’t spend much time in either as it’s not registered yet. I just tested p4 and p6 by back probing into controller with a sewing needle. I have b+ voltage on p4 with switch in either position. I have b+ Voltage on p6 in DH and 0v on DL.

05’s were stock with 12.44 gearboxes. They also had the T3 controller stock. I forget what the exact problems were on the T3, but I recall it’s kind of a steaming pile compared to the other controllers used before and after it. A lot of hardcoded settings in there that can’t be changed even with a programmer was one of the issues.

That may be the performance issue. It appears not to be from the warning light.

Got the diagram and manuals.
No indication of reduced performance from warning light being on.
The motor temperature switch goes directly to controller pin 21.
One way communication to dash.

Dumb question maybe?
Have you reset the warnings by power cycling?
I find it hard to believe, under normal conditions, that the controller is sending warning data if p21 is high. P21 should be ■■■■■ proof. Shorting high or low can’t damage it. Warning light driver in the display could have shorted.

(I guess i d i o t) is a trigger word. :slight_smile:
Reminds me of this gift from a buddy!

I have cycled the master power switch with the warning light still illuminating directly after. I’m not sure if the driver is shorted internally for the indicator because if I key on while I’m charging, I get the charge indicator and the temp light remains off. That’s the only time it goes out.

If you have any tests you think I can conduct, let me know. I have plenty of tools and well versed in electrical diagnosis using picoscope, dvom and have amp clamps. I just don’t have another car to compare with and I’m a little limited in manuals.

I’m stumped on this one.
Wiring is pretty straight forward.
There may be other things that can illuminate the temperature warning. just don’t know.

Charging is a clue. The controller is off during charging. No communication from controller to dash.
That means the controller IS responsible for the warning. No fault codes, so it’s not controller over heating.

Unless someone knows how it works, swapping controllers is all I got left.

Does someone have a T3 to monitor?
This example is a different controller. It shows seat switch logic position.

I wonder if T3 will show P21 logic in Sentry?
If I get time, will try a T4, but my Sentry computer is down.

I’ll toss this out here too just for kicks.

Wild guess- Just for fun, check P21 reference to P20 (Gnd). Maybe the controller is getting a bad Gnd ref? It looks like the other end of P20 goes to the PSDM (shunt) and I’ve seen a few of those with burned contacts on the PCB.

I’m sure you don’t need to be made aware of the dangers having two bare sewing needles that close together.

“Don’t cross the streams! It would be bad” -Egon