How to diagnose a faulty ECU? I have one that gives the only CEL being a steady blink.

Any good tests besides putting the ECU in another car (which I do not have access to)?

 

When you jumper the SCS connector it's supposed to turn on the light continuously, if there are NO error codes stored. My Helm book says if you jumper the connector & the light doesn't come on, then the ECM is bad.

 

what year is the ecu?

 

1995 jdm p28......flashing light could be code 1 repeating but the car should run, if rough i would imagine

 

Is it flashing a short flash or a long flash. It should still run normal when the light comes on for the O2 or the intake air temp.

The only problem I can see is that you might have plugged the Intake air temp connector into the IAC and the IAC connector into the Air-temp Sensor. If you did this the you fried the intake air temp sensor and the IAC circuit on the ECM board.

Check to see what connector is where.....The IAC will have a connector with a blue and a Black/yellow or yellow/black depending on year. The air temp will have a connector with the colors Green and Red. If you did have these crossed then I would change them back and get a new air-temp sensor and send the ecu to someone that can fix the circuit. If you want, you can take the ecu out and open it up and see if the circuit has been fried. You will see it right away if it has it will have burn marks. If you do let me know, you can send it to my shop and I can fix it for you.


Modified by RedZone at 1:18 AM 5/12/2004

 

no, iat and iac good, not cnfusable on my harness but the correct wires..we also traced out all ecu leads to injectors, dizzy and the straight wired vtec, o2, ks, etc. and all good/ i cannot see any obvious burned area on ecu board...

i am going to take the ecu and the s200 hondata and try them on a obd1 car friday and see if that does it...if it does not then i will have to suspect the BRAND NEW dizzy king dizzy...

i checked these (the seven wires all the way thru the harness, jumper and to the ecu and they are correct

any other ideas.
??

ps my crvtec powered 87 crx just went 218 to the tire @ 8800 with not enough injector so will go to 370's...this runs on obd0 pr3 with apex vtec controller. hopefully car will be a bear at 1700 lbs. maybe obd0 not so bad after all!