I decided to swap my ECM out in my 1995 accord LX 5 speed. I went to my nearest "pick n pull" junkyard. I couldn't find a single 5 speed to pull an ECM from in the junkyard, so I decided to pull one from a 1995 automatic. The serial numbers are off, but not by much. I swapped the ECM and havent had any problems with stalling out, but my idle RPM did jump up by almost 500 RPM. Whoa. I followed the service manual instructions to adjust the idle RPM, but I can only get it down to about 900RPM.

I guess the question is, is it ok swap out the ECM from a manual transmission and put in an automatic ECM? Everything else seems to be working fine and my car has not been stalling out since I put it in. Before the swap, my main relay was freaking out under the dash and causing the engine to shut off (yes I tried replacing the main relay first). Are thrre any dangers or factors that Im overlooking that may endanger my accord? Any information is greatly appreciated. Thanks for the time.

 

• 5 speed: P0A-???
• Automatic: P0A-???

 

You are fighting the ECU to get the idle set.

You really should use the ECU from a manual transmission 94/95 LX/DX.

If you know how to solder parts on a circuit board, you can convert the AT ECU to a MT ECU by moving some resistors or jumpers on that board. Search the web. You can also compare your two ECU boards to identify the difference of the resistors.

 

Thanks, PAHonda. I'll likely order a used MT ECM from eBay although I truly appreciate the input and suggestions.

Roader, the MT computer SN was:
37820-P0B-A01 380-118730

The AT computer SN was:
37820-P0B-A51 381-251096

Thanks for your time, guys. I'm still very appreciative for any additional information that you all may have to offer. Thanks

 

your RPM's may be a tad high but you should be able to run the auto ECU for quite a while...

i assume it didn't throw any codes..?

 

The automatic ECM has not thrown any (new) codes. The MT ECM was throwing code 6 (engine coolant temp sensor) before the swap and the AT ECM still throws the same code. I replaced the sensor but the check engine light remains on after resetting.

 

It's an LX, not an EX. My bad. P0B is the right ECU.Wiring? The FSM has excellent diagnosis steps for an ECT CEL. You've replaced the ECT sensor and the ECU, maybe there's something flaky in between. And since the ECU swap didn't fix the ECT CEL, you might want to put the auto ECU back in. A DVM and some time should find the problem. An open ECT circuit would cause the ECU to think the coolant temp is low all the time, resulting in a high idle.

 

And the "sensors" can be a bit confusing. The ECT is the two wire sensor on the end of the cyl head under the dist. As roder stated, it will vary resistance based upon temp. So if you measure the resistance between the two pins on the switch and note the temp of the sensor....that will tell you if the sensor is working. See pic

Search "pgmfi.org", there is a "how to" on the auto to manual ECU conversion.