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Tachometer AEM Series 2 ECU

Joined
31 March 2011
Messages
386
Location
Washington State
Hello Prime,

Asking for your help. After installing a CTSC and an AEM Series 2 ECU, my tachometer is no longer working. The installer suggested that the AEM series 2 could be the cause for the tachometer to no longer function. Has anyone experienced this problem and know of a solution? I am unsure what is the cause for the tachometer to no longer function. The installer has attempted to look for the issue by testing the electronic connections with no success. Does anyone have any idea of what may be happening?

The installer suggested that they could do more searching but it could take another 4 hours which is up to $400 in labor. Ouch!!!

Please respond with any solutions.

Thank you
 
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Try starting the car on the stock ECU and see if the tach works.

Of the top of my head I would check to make sure all your grounds are good. Always unusual electrical problems if there are any ground problems.
 
I am not familiar with the details of the AEM ECU; but, most cross platform ECUs will have a digital output port which is software configurable to provide a tach signal usable by the vehicle tachometer. Check the software setup for the AEM. According to the Honda Service Manual, the tach is looking for a pulse rate of 300pulses/100 RPM (I don't know why they just don't specify 3pulses/RPM which is what any 6 cylinder engine should be). Solidol's suggestion of checking for pulses at the output port on the AEM is an excellent place to start.

If its a software goof, the installer should not charge you anything for the fix. That should be part of the original installation.

Beyond that, just obvious stuff. Make sure the electrical connections are complete.
 
Try starting the car on the stock ECU and see if the tach works.

Of the top of my head I would check to make sure all your grounds are good. Always unusual electrical problems if there are any ground problems.


are you getting tach signal at tach test port?

I am not familiar with the details of the AEM ECU; but, most cross platform ECUs will have a digital output port which is software configurable to provide a tach signal usable by the vehicle tachometer. Check the software setup for the AEM. According to the Honda Service Manual, the tach is looking for a pulse rate of 300pulses/100 RPM (I don't know why they just don't specify 3pulses/RPM which is what any 6 cylinder engine should be). Solidol's suggestion of checking for pulses at the output port on the AEM is an excellent place to start.

If its a software goof, the installer should not charge you anything for the fix. That should be part of the original installation.

Beyond that, just obvious stuff. Make sure the electrical connections are complete.

I contacted Chris at SOS and he believes the problem has to deal with the AEM software. I plan to meet with Chris to check this out next week. I will reply with an update next week. Thanks for the ideas for solutions.

JP
 
I'm assuming you got this sorted out? Mind sharing what the issue/solution turned out to be? I have a similar issue ruining my life at the moment.
 
Apparently there is a known issue with the Infinity and AEM acknowledge the issue and offer a repair under warranty.

It affects the VSS which goes hand in hand with the tach.

However the OP has a Series 2 and not a Infinity but thought it was worth replying in case anyone else has the issue.
 
Was not able to meet with Chris. Finally brought the NSX in to be checked out by a local mechanic that works on the NSX. The mechanic called Chris. Because I have a 98 they were not able identify the problem. NSX's 91-94 SOS is able to resolve the AEM tachometer issue.

1) Checked electrical wiring linked to AEM and OEM ECU, no issues found.
2) AEM series 2 functioning correctly.
3) Pulled the dash out to look over the gauges. No issues found.
4) Checked OEM ECU and looks like the signal from the ECU to register the tachometer is not functioning.

We we believe the issue to be that the OEM ECU is not working. Anyone have any additional thoughts? Are we on the right track?

Thanks
JP
 
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I had a similar issue and it was in fact the OEM ECU, for some reason or another it was no longer sending tach signal out. Ultimately if PIN C7 at the ECU is not sending 6 pulses/RPM (Watch volts climb as you rev the engine) then the ECM is your issue.

The fix was as follows;

- Connect to the AEM and find a free pin that you can configure as an output signal. (I think we used Low Side 1, Pin A2)
- Add an additional wire/pin to the AEM connector at the location mentioned above assuming you don't have any spares (I Didn't), because we didn't have a pile of spare AEM pins around we used a random Honda pin and made it work as best we could by jamming it in... hey, it works.
- Connect to the AEM and configure this PIN as a TACH OUTPUT in the AEM
- Configure the TACH OUTPUT signal as 6 pulses per RPM. (Screen will show the crank teeth being picked up by crank angle sensor, you need to add 6 pulses, so spread them out equally over the teeth so that a every 6 teeth a pulse is sent out IE: 36 teeth/6 = 6 teeth per pulse)
- Run the new TACH OUTPUT wire from the AEM over to the OEM ECU
- Cut the wire coming out of the OEM ECU plug at C7 about 1.5" back (Double check that pin number)
- Connect the new TACH OUTPUT from the AEM to the harness wire @ C7 that you just cut, tape off the wire coming out of the OEM ECU plug, you will be abandoning this wire.
- Start the car and watch as your tach comes to life, try changing pulses a couple times if it doesn't come alive...

You're tach signal will now come directly from the AEM, as will tach signal at the test connector in the engine bay.

AEM tech thread which may help you understand setting the configuration of the AEM TACH OUT.
http://aemelectronics.com/?q=forum/tacho

Download the S2000 AEM Series 2 EMS manual, this is the AEM EMS that SOS uses for the NSX P&P solution. http://aemelectronics.com/files/instructions/30-6052 Series 2 Plug & Play EMS.pdf

Send me a PM if you need any help and I can walk you through the config over the phone or have my tuner do it etc.
 
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I had a similar issue and it was in fact the OEM ECU, for some reason or another it was no longer sending tach signal out. Ultimately if PIN C7 at the ECU is not sending 6 pulses/RPM (Watch volts climb as you rev the engine) then the ECM is your issue.

The fix was as follows;

- Connect to the AEM and find a free pin that you can configure as an output signal. (I think we used Low Side 1, Pin A2)
- Add an additional wire/pin to the AEM connector at the location mentioned above assuming you don't have any spares (I Didn't), because we didn't have a pile of spare AEM pins around we used a random Honda pin and made it work as best we could by jamming it in... hey, it works.
- Connect to the AEM and configure this PIN as a TACH OUTPUT in the AEM
- Configure the TACH OUTPUT signal as 6 pulses per RPM. (Screen will show the crank teeth being picked up by crank angle sensor, you need to add 6 pulses, so spread them out equally over the teeth so that a every 6 teeth a pulse is sent out IE: 36 teeth/6 = 6 teeth per pulse)
- Run the new TACH OUTPUT wire from the AEM over to the OEM ECU
- Cut the wire coming out of the OEM ECU plug at C7 about 1.5" back (Double check that pin number)
- Connect the new TACH OUTPUT from the AEM to the harness wire @ C7 that you just cut, tape off the wire coming out of the OEM ECU plug, you will be abandoning this wire.
- Start the car and watch as your tach comes to life, try changing pulses a couple times if it doesn't come alive...

You're tach signal will now come directly from the AEM, as will tach signal at the test connector in the engine bay.

AEM tech thread which may help you understand setting the configuration of the AEM TACH OUT.
http://aemelectronics.com/?q=forum/tacho

Download the S2000 AEM Series 2 EMS manual, this is the AEM EMS that SOS uses for the NSX P&P solution. http://aemelectronics.com/files/instructions/30-6052 Series 2 Plug & Play EMS.pdf

Send me a PM if you need any help and I can walk you through the config over the phone or have my tuner do it etc.


Thanks very much for the info. Good to know there is a fix. I will share this information with the mechanic. It is so annoying not having a tachometer working.
 
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