Aim Solo 2 DL incompatibility with E36 ECU tach signal

[Evergreen Dan]

Solo 2 DL, firmware 2.30.10 with Power+RPM cable. The problem is that the ECU in the E36 supplies a constant 4.6 volts when idle (e.g. key off). This voltage continually turns on the Solo 2, even if the 12volt external power is not supplied, draining the battery.

This is being reported to AIM. You need to unplug the power cable from the Solo 2 DL to avoid this problem, connecting it just before each run. If you wanted to, you could install a small reed (or other) relay on the RPM line, closing the contacts only when power is supplied. Alternatively, I bet an in-line non-polarized capacitor of appropriate value would work, but I haven't tested it. I reassembled the trim on my street car with sufficient difficulty that I'm waiting to see if this is fixed in firmware.

Note that the "Wake Up on ECU" option in the Solo 2 DL setup currently does not affect this behavior in any way. It seems to apply only to ODB or CAN cables, which supply power continuously.

On an E36, the "engine speed" square wave signal can be obtained from the Datalink pin 1 or a variety of other locations, including the ECU, the cluster, the EWS, the slip angle sensor, and other locations. It is black wire on my E36/8. I took it from the cluster, along with switched power (violet/yellow) and ground (brown).

Hope this helps someone else who is scratching their head why their Solo keeps turning back on by itself.

[jdehaan]

I, too, have my solo 2 DL hooked up to tach for RPM. Does anyone have an issue with the solo powering off mid session? In some sessions the LED indicator lights don't work and it restarts itself randomly.

[Fjacobs1000]

resurrecting an old thread...i have an rpm signal from the obd pin 1, but the values seem way way off. i *think* i need to set the rpm 'factor' in race studio3. anyone know what that rpm factor value should be?

[olemiss540]

I had to wire in a resistor to correct the rpm readings on my AIM dash I believe. Let me see if I can dig up the thread but it was a simple fix.

[32Racing]

I had to wire in a resistor to correct the rpm readings on my AIM dash I believe. Let me see if I can dig up the thread but it was a simple fix.

Did you ever find the thread?

I am looking to put a Solo 2 DL in my 1999 E36 M3, but if RPM doesn't work with it, I'm not sure the value is there vs a normal Solo 2

How well would the Solo 2 DL be at giving a shift light? Is the rate quick enough?

[golgo13]

It is my understanding that the processor in the DME in the E36 has too low of a refresh rate to be useful. I think it's like 1Hz or a 1 second update.

[aeronaut]

I think we're discussing 2 things in this thread.
Yes, you can use an output directly from the DME on a 95 as the rpm input to an AiM dash that has the digital rpm channel input. I'm pretty sure I use a /3 factor to get the right rpm.
That's very different than reading the rpm via OBDII protocol, which yes, I've read (no experience) that the E36 OBDII refresh rate for the rpm is too slow to be of use.

[olemiss540]

Did you ever find the thread?

I am looking to put a Solo 2 DL in my 1999 E36 M3, but if RPM doesn't work with it, I'm not sure the value is there vs a normal Solo 2

How well would the Solo 2 DL be at giving a shift light? Is the rate quick enough?

Its a pull up resistor. Check out the last post in this link:
https://www.corvetteforum.com/forums...-rpm-line.html

Mine is an LS swap so your resistor value may be different. Hope this helps troubleshoot a way to get it to work!

[golgo13]

I think we're discussing 2 things in this thread.
Yes, you can use an output directly from the DME on a 95 as the rpm input to an AiM dash that has the digital rpm channel input. I'm pretty sure I use a /3 factor to get the right rpm.
That's very different than reading the rpm via OBDII protocol, which yes, I've read (no experience) that the E36 OBDII refresh rate for the rpm is too slow to be of use.

Okay, then I'm confused. I wasn't aware that you can tap into the K-CAN data stream to get accurate data for an AiM device.

[aeronaut]

Okay, then I'm confused. I wasn't aware that you can tap into the K-CAN data stream to get accurate data for an AiM device.

I'm pretty sure I used the signal from the DME to the instrument panel labeled "Crankshaft RPM speed signal TD" .
I can confirm tomorrow if it would help someone.

95-DME.jpg

[32Racing]

I'm pretty sure I used the signal from the DME to the instrument panel labeled "Crankshaft RPM speed signal TD" .
I can confirm tomorrow if it would help someone.

95-DME.jpg

Right, I would pull from the instrument panel black wire, NOT the OBD-II port (because it is too slow). If the black wire can drive the tach, I would think it could drive the AiM, right? Isn't that what some use for their Cartek and Shift-P2 shift lights?

[mslevin]

Right, I would pull from the instrument panel black wire, NOT the OBD-II port (because it is too slow). If the black wire can drive the tach, I would think it could drive the AiM, right? Isn't that what some use for their Cartek and Shift-P2 shift lights?

I use the black wire that previously went to the dash, I no longer have a stock cluster. My AiM MXL2 has an RPM input wire. Connect, set the /3 thing, done.

For a Solo 2 DL, you'll need something like this: https://www.bimmerworld.com/Gauges-D...RPM-Cable.html

I'm not sure if the DL can support additional inputs, via something like the AiM CAN channel expansion.

[aeronaut]

Right, I would pull from the instrument panel black wire, NOT the OBD-II port (because it is too slow). If the black wire can drive the tach, I would think it could drive the AiM, right? Isn't that what some use for their Cartek and Shift-P2 shift lights?

Bingo.

- - - Updated - - -

I use the black wire that previously went to the dash, I no longer have a stock cluster. My AiM MXL2 has an RPM input wire. Connect, set the /3 thing, done.

For a Solo 2 DL, you'll need something like this: https://www.bimmerworld.com/Gauges-D...RPM-Cable.html

I'm not sure if the DL can support additional inputs, via something like the AiM CAN channel expansion.

I'm about to pull my dash out also. It's kinda useless now and goes dark on it's own anyway.
It's odd that the ground for the fuel sensors and (I think) speed sensor, is supplied from the cluster?!
There's also a speed signal from the IC to the DME but I've already routed the differential speed sensor to the DME, and that works.

[mslevin]

I'm about to pull my dash out also. It's kinda useless now and goes dark on it's own anyway.
It's odd that the ground for the fuel sensors and (I think) speed sensor, is supplied from the cluster?!
There's also a speed signal from the IC to the DME but I've already routed the differential speed sensor to the DME, and that works.

Yep, the dash in these cars is really more than just a display unit. Some groovy stuff goes on in there.

Yeah I did the same, VSS from diff to ECU directly. Apparently you can take any high freq signal, such as the cam position sensor, and wire it to the ECU. All the ECU needs to see is a speed, not a correct speed

[aeronaut]

Interesting. So it sounds like the speed signal into the DME is a "I'm moving" signal rather than a "I'm going some specific speed and am going to use that speed to do something" signal.

Before I tapped the diff speed signal, when the cluster would go dark, I'd lose a noticeable chunk of HP above ~3k until I banged on the cluster to get it to light up. lol.

[mslevin]

Interesting. So it sounds like the speed signal into the DME is a "I'm moving" signal rather than a "I'm going some specific speed and am going to use that speed to do something" signal.

Before I tapped the diff speed signal, when the cluster would go dark, I'd lose a noticeable chunk of HP above ~3k until I banged on the cluster to get it to light up. lol.

Yep. ABS/traction control uses wheel speeds, not diff speed. The OBC speed "limiter" (the ding) likely uses the VSS signal, but apart from that I think it's just an "I'm moving" signal.

Interestingly, I'm pretty sure the "launch control" that most tuners give you is actually repurposing the soft rev limiter that sets in place when you lose diff speed signal.