Charles Dehn

i decided to take the UIM back off and check the ground wires themselves before hacking into the harness more. my BAC valve was clicking repeatedly with the key to ON and was also firing off the solenoid rack due to an intermittent connection at the connector itself so i figured this would be a good time to just take the harness off and give everything a once over, replace the BAC and injector connectors if not just for peace of mind.

i tested resistance between the 2 main ECU ground wires that lead from the spade back to the ECU connections and the ohms came back at 0 at all 4 ECU terminals. I even de-loomed the harness, traced checked every single ground wire for resistance and they all check out at 0 ohms. the spade splice connector you mentioned looks fine visually, no corrosion or discoloration and i checked for resistance from the main ECU ground spade directly to the staple and then from the staple to the ECU ground terminals and it all checks out at 0 ohms.

i also checked my meter against the battery ground as you suggested. with the negative terminal wire disconnected, positive terminal connected and my multimeter leads on the negative terminal and the lead coil bracket, my meter read 12.5ishV. with the negative wire connected my meter read at a steady 2.5mV. should such a small amount of voltage be a concern?

is it possible i just purchased another bad ECU? maybe my multimeter is lying to me? it seems to me that the ECU ground is ok but i suppose checking the harness with a multimeter could produce different results than when 12v is sent through it under load. i will probably still add the 4 extra ECU ground wires anyway for peace of mind, but if the grounds were ok in the first place it may not be the ultimate culprit

satch

iTrader: (1)

You can open up the ECU and see if there is apparent damage.

And did you try grounding pin 1G to see if it allowed the ECU to fire the injector pulse w/key to start?

And did you correct the clicking solenoid problem? The B/W wire which powers the solenoids is the same wire powering the ECU. If the problem w/the solenoids which you had/have was a result of the B/W wire then it would also affect the ECU.

Charles Dehn

i did take both the top and bottom cover off the ECU to check for burns and cold solder but couldnt find anything apparent

i also did test for injector pulse with 1G grounded out and i got nothing. the clicking solenoid problem only developed after i took the UIM off the first time. as i was searching for it, i traced it to the BAC and as i went to take the connector off, the clicking stopped suddenly as soon as i moved it. since it gets power from the same wire as the solenoid rack this makes sense. i also found a significant amount of resistance on the B/W wire routed from the yellow and blue solenoid connectors, around 29 ohms. I cut a slit in the wire leading to staple from the yellow connector and tested the resistance and got 0 ohms so it seems the culprit is the connector itself.

i replaced the BAC connector and double checked resistance between all of the injector wires running to the ECU, to the resistor pack and from the resistor pack to the front harness connector (FEM-02) that runs 12v from the main relay. now im in the process of double checking the rest of the harness and re-looming it.

i also took the engine harness out and deloomed it cuz im mad at this point hahah and want to root out and destroy any possible electrical issues that could arise from the ground wires there and I also wanted to double check the modifications i made to it since i converted my car from an automatic. the main ground wire that runs from the battery to the driver shock tower and starter motor checks out with no resistance. should i maybe add another ground wire directly to the motor? before i took it off, i checked resistance between the ECU ground under the UIM and the battery and got 2 ohms. is that enough to cause weird problems?

satch

iTrader: (1)

It seems the grounds are good enough but did you ever test the ohms of the injectors because if they just happened to be wrong they could damage the part of the ECU responsible for firing them but then again there should be noticeable damage to the ECU board. Also, make sure the connectors FEM-01 and 02 are solid as issues could arise from an improper connection. And do you have a spare CAS? And have you tried unplugging the AFM while jumpering the fuel check connector to see if the AFM is preventing the injectors from firing. And make sure the sheath on the CAS wiring is grounded properly as well. And are you certain you checked the ECU to see if the injectors are being fired as it pertains to the primary injectors and not the secondary ones for only the primary injectors are used to start and idle the car.