daughterboard com error

scttydb411 · Post by **scttydb411** » Sat Jun 02, 2007 10:28 pm

tuned a cust k24 ek that kept having connectivity issue w/ the usb and had a serial comm cel.

few weeks pass and cust begins to get cel and rough idle, driveability, etc. he connects to the laptop and is now getting daughterboard error cel.

anything to do, or just send the ecu in to be checked. it is a cust supplied ecu that was originally sent to hondata for kpro install.

Post by **Hondata** » Sun Jun 03, 2007 9:50 am

You've seen the sticky?

http://hondata.net/forum/viewtopic.php?t=4877

Almost all the time it is from either the battery being relocated or the battery being on its last legs. The pertentent questions are 'has the car been jump started recently?' followed by 'why did it need to be jump started?'

The rough idle is unrelated to the daughterboard error. None of the engine swap harness I've examined supply keep alive power to the ECU. That means that the ECU never performs idle learn and the idle will never be smooth. The idle valves get sticky too.

If the comms error is P0600 then you can fix this by disabling the mulitpexer.

The connectivity error needs investigation - it usually is a ground loop from an incorrect harness or missing ground. Most people forget the timing cover side engine ground for some reason.

kornsined · Post by **kornsined** » Mon Jun 04, 2007 5:24 pm

Hondata wrote: The rough idle is unrelated to the daughterboard error. None of the engine swap harness I've examined supply keep alive power to the ECU. That means that the ECU never performs idle learn and the idle will never be smooth. The idle valves get sticky too.

I never knew that. Good heads up.

There is no way to get the ECU to learn idle with a swap harness then? Anyway around this?

Post by **Hondata** » Tue Jun 05, 2007 8:43 am

It is simple - the ECU has to be wired into the vehicle in the same way as a stock RSX. The ECU gets keep alive power from the coil side of the main relay, so specifically the main relay needs to be wired the same as a RSX.

The RSX main relay wiring is different from an EG, DC or EK relay wiring. You can't use the relay in those cars, and it can not be converted over. You need to install a new main relay, wired as per the RSX. None of the harnesses do this.

The ECU main relay output gets a trickle of voltage from the coil side of the main relay. This output is designed to sink current (ground) the main relay to power the rest of the ECU when the ECU detects the ignition has been switched on. Most engine swaps put +12V onto the main relay output, which burns out the component in the ECU as soon as the batery is connected. To solve this problem the swap harnesses then use ignition power to supply power to the ECU rather than the main relay output. This is not the right way to do it, and causes problems.

Razathorn · Post by **Razathorn** » Tue Jun 05, 2007 11:06 am

Hondata wrote:It is simple - the ECU has to be wired into the vehicle in the same way as a stock RSX. The ECU gets keep alive power from the coil side of the main relay, so specifically the main relay needs to be wired the same as a RSX.

The RSX main relay wiring is different from an EG, DC or EK relay wiring. You can't use the relay in those cars, and it can not be converted over. You need to install a new main relay, wired as per the RSX. None of the harnesses do this.

The ECU main relay output gets a trickle of voltage from the coil side of the main relay. This output is designed to sink current (ground) the main relay to power the rest of the ECU when the ECU detects the ignition has been switched on. Most engine swaps put +12V onto the main relay output, which burns out the component in the ECU as soon as the batery is connected. To solve this problem the swap harnesses then use ignition power to supply power to the ECU rather than the main relay output. This is not the right way to do it, and causes problems.

So existing K series swap harnesses will damage the K series ecu, or the harnesses have been changed to not damage the ecu, but lack the functionality you're describing.

It seems pretty bad if swap harnesses are damaging ecus.

Post by **Hondata** » Tue Jun 05, 2007 6:55 pm

I think the initial attempts to make harnesses resulted in the ECU main relay output burning out. Since then, the harness manufacturers removed the main relay output and just used the switched ignition to power the ECU.

Most swap harnesses do not damage ECUs, but a lot do. It is frustrating from our end because the KPro always gets the blame.

For what it is worth, when I did my K20 engine swap in 2003 the harness I made started the engine up first time, without errors, and has worked ever since. The wiring diagram I made is the one commonly posted around the internet. It's not rocket science. Sigh.

kornsined · Post by **kornsined** » Tue Jun 05, 2007 7:12 pm

I don't think 7thgen civics would have this problem then since they are very similar to the RSX.

I understand the concern from you guys. I guess it's easier to point the finger to the ecu then the harness.

kornsined · Post by **kornsined** » Wed Jun 06, 2007 5:42 pm

This error seems odd and something simple.

Post by **Hondata** » Thu Jun 07, 2007 9:52 am

Yes, the 7th gen civic is much easier for engine swaps because the wiring is very close to the RSX. Some models have wideband o2 sensors as well.

It sounds like an output or sensor from the ECU is being shorted to either 12V or ground. This then shuts the ECU voltage regulator down and therefore the ECU. However it is odd for this to happen without being vibration induced.

It might pay to pull the lid off the ECU and check the KPro is secure. Don't re-tighten the screws unless they are loose, as they are locktited in. Just check the connectors are making full contact and the screws are not loose.

Otherwise, what error code are you getting? Why was the alternator and battery replaced? (BTW 14.58V sounds high). Could this be related to temperature (electronics often fail with extremes of hot or cold).

kornsined · Post by **kornsined** » Thu Jun 07, 2007 5:11 pm

Checked the ecu and connections. Nothing seemed loose.

The only error code I got was "Daughter board communication error". I did recently (prior to this problem) turn my OBDII on to check for any DTC's and got P1298 and the secondary O2 sensor error. Although I am not running a cat so I figured this was normal.

After I cleared the DTC's and "set readiness".

The reason for changing the alternator was a loose/broken connection on the alternator (power connection to the battery). The battery was replaced since it has died numerous times from various stupid incidents (lights left on, etc.).

kornsined · Post by **kornsined** » Fri Jun 08, 2007 4:40 pm

I think I may have found the problem. I checked the fuse box and the a/c condensor relay was loose. I secured it and haven't had the problem come up again.

kornsined · Post by **kornsined** » Sat Jun 16, 2007 8:09 pm

Problem alleviated.

Post by **Spunkster** » Mon Jun 18, 2007 3:39 pm

This vehicle appears to have a battery voltage problem, or a grounding issue. You will need to check these things. Since it happens at high RPM it may be a loose wire that becomes known when there is more vibration.

kornsined · Post by **kornsined** » Sat Jun 23, 2007 5:37 pm

Nevermind

kornsined · Post by **kornsined** » Fri Jun 29, 2007 12:20 pm

Hondata wrote:Yes, the 7th gen civic is much easier for engine swaps because the wiring is very close to the RSX. Some models have wideband o2 sensors as well.

It sounds like an output or sensor from the ECU is being shorted to either 12V or ground. This then shuts the ECU voltage regulator down and therefore the ECU. However it is odd for this to happen without being vibration induced.

It might pay to pull the lid off the ECU and check the KPro is secure. Don't re-tighten the screws unless they are loose, as they are locktited in. Just check the connectors are making full contact and the screws are not loose.

Otherwise, what error code are you getting? Why was the alternator and battery replaced? (BTW 14.58V sounds high). Could this be related to temperature (electronics often fail with extremes of hot or cold).

When I put in a new battery last weekend the voltage was now at 14.68 at idle. As you stated before unusually high. Now when I had the OBDII enabled it said the following errors P1298 ELD high voltage and P0140 Secondary 02 heater malfunction. I know the P0140 is from running no cat but is the P1298 related to having no cat as well? Or is it an indication that my ELD is toast and possibly the cause of this daughter error?

Is this something I should look at replacing?