ECU (w/K-Pro) went bad. Is repair/replacement available?

Hondata model coverage & ECU application questions.
Post Reply
MacLotus
Posts: 10
Joined: Mon Jul 26, 2010 8:33 am

ECU (w/K-Pro) went bad. Is repair/replacement available?

Post by MacLotus »

I believe my ECU may be damaged (according to the Honda manual), but I'm certain the K-Pro is working fine. Is it possible to send it in and have my K-Pro board swapped to a new PRB ECU board?
Ken
User avatar
Spunkster
Site Admin
Posts: 22737
Joined: Fri Sep 20, 2002 5:06 pm
Location: Hondata

Re: ECU (w/K-Pro) went bad. Is repair/replacement available?

Post by Spunkster »

What exactly is the problem?
MacLotus
Posts: 10
Joined: Mon Jul 26, 2010 8:33 am

Re: ECU (w/K-Pro) went bad. Is repair/replacement available?

Post by MacLotus »

The portion of the ECU that controls dual-rate battery charging is not working properly. After following the Honda manual's troubleshooting procedure, it says replace ECU. New battery and alternator, plus cleaning all ground points and countless hours of troubleshooting. After sitting a day or two, start-up and battery charges fine at 14vdc+, then after 10-15 minutes stops charging... As though it shutdown.

I think I damaged the ECU by using the 'Battery Disconnect Switch' before the ignition switch. This 'race car' switch physically disconnects the battery from the car, but I've since learned that could damage the alternator (which it did) and the ECU. I had hoped it didn't, but now I'm pretty certain it did.
Ken
User avatar
Hondata
Site Admin
Posts: 10434
Joined: Thu Aug 15, 2002 12:13 pm
Location: Torrance, CA
Contact:

Re: ECU (w/K-Pro) went bad. Is repair/replacement available?

Post by Hondata »

None of the RSX era ECUs actually control the alternator voltage - they always are internally regulated (~ 14V). I'd disconnect the ALTC wire from the ECU.
Hondata
MacLotus
Posts: 10
Joined: Mon Jul 26, 2010 8:33 am

Re: ECU (w/K-Pro) went bad. Is repair/replacement available?

Post by MacLotus »

I disconnected the Alt C wire a while back. New Denso alternator. Voltage output measured at alternator. 12vdc IG circuit good. Charge of 14vdc output is there.... then it drops out. I've been chasing this gremlin for two years now, although I don't drive it much.

So if I understand what you're saying, the alternator will always provide an output with only the Alt IG wire and Alt B (battery charge cable) connected, although idle speed will remain constant.
Ken
User avatar
Hondata
Site Admin
Posts: 10434
Joined: Thu Aug 15, 2002 12:13 pm
Location: Torrance, CA
Contact:

Re: ECU (w/K-Pro) went bad. Is repair/replacement available?

Post by Hondata »

The alternator only needs B & IG to work. L is light, C is control, FR is field voltage (input to ECU).

I'd check that the ALTC connection is not floating to ground (which is low output mode).
Hondata
MacLotus
Posts: 10
Joined: Mon Jul 26, 2010 8:33 am

Re: ECU (w/K-Pro) went bad. Is repair/replacement available?

Post by MacLotus »

Good idea. I'll check that out.
Ken
nanim0n
Posts: 1
Joined: Tue Apr 30, 2013 4:12 pm

Re: ECU (w/K-Pro) went bad. Is repair/replacement available?

Post by nanim0n »

Sorry to bring this back from the dead but I think my ecu is bad too . having fuel problems . not priming . switched my ecu into a friends car and did the same thing .
User avatar
Spunkster
Site Admin
Posts: 22737
Joined: Fri Sep 20, 2002 5:06 pm
Location: Hondata

Re: ECU (w/K-Pro) went bad. Is repair/replacement available?

Post by Spunkster »

Please start your own thread as it has nothing to do with this post. Follow the posting guidelines.
Post Reply