I have had my ECU capacitors replaced and upon installing the ECU, the double wiring harness plug, with the bolt, won't tighten down, it acts like I have stripped the bolt, which I have not done. It appears that the threads end on the bolt to an empty shoulder on the bolt and it only tightens past the threads and spins freely at the shoulder. The rebuilder states that the plug needs to be tight and that the plug is not engaged all the way. Anyone encounter this problem?

Back story, the car ran very poorly until I disconnected the volume air flow meter sensor connector. Pins 2, 3 & 4 were reading 5v. Only pins 2 & 4 should have the 5v reference signal. Pin 3 should be signal back to the ECU. I isolated the wire down to the ECU and found that the computer is feeding 5v to the volume air flow meter sensor. Thus the replacing of the leaking capacitors. Now I have no spark. This is the reason for the post.

Hello,

It appears as if the Bolt that holds the Connector in place got snapped out of its proper position, here is an eBay listing that has pictures of what that connector should look like, the Tie-Down Bolt appears to be hidden much deeper within the housing than in your case. See how much Back and Forth play the Bolt has inside of the Housing, from what I understand, it should barely be there, if it can travel the entire length of the Bolt, the Connector is likely damaged, you will need to take it apart to investigate further.

Hope this helps and best of luck!

Thanks for that, I will look into it and let you know what the outcome is.

So, that bolt has two sets of threads, one at the end that you can see and more threads above the blank shoulder near the 10mm hex head. There is a metal clip that engages the threads at the 10mm hex and regulates how the bolt engages into the ECU. It was not loose, there is no play, the bolt moves in or out as you spin the bolt. Though the fact that I was still unable to tighten the bolt completely. Therefore, I added a split washer just under the bolts hex head and I can now tighten the connector and the harness connector will not engage any further into the ECU. However, this still has not solved the issue. The CEL will not come on with the initial key on engine off, no spark and no injector pulse, as if the ECU is not commanding the grounding to trigger. The rebuilder still is insisting that the ECU pins are not engaging completely to the harness connector. and I haven't worked on enough of these to really know..

It doesn't really matter at all if the Bolt is Tightened, so long as the Pigtail is seated Fully into the ECU Connector, here is a picture of what that should look like. The Bolt is there only as a Secondary Retention Mechanism, ensuring that this connector won't come out on a Bump or other rough terrain for example, and just like any other connector with a broken clip, it can still function without a Bolt in place, so long as you, again, make sure that it is Seated all the way.

In all honesty, from your description, it sounds like you have a bummed ECU. Who rebuilt it for you?

Hope this helps and best of luck!

I would say, looks good. It was Cowboy Bill @ Japanese ECU Repair that did the cap replacement. He keeps insisting that the connection isn't complete. He tells me he will re-test the ECU. But the question is, can he test the function of the ECU? OK, he can test certain components, but why have I lost function of the ECU? Anyway, just venting. If anyone has any function test that can prove whether the ECU is functioning properly, it would be greatly appreciated.

I know Josh Beaumont at Relentless Motorsports TX has a SC300 test car he uses to test the ECUs he fixes. May want to try him?

Connector in the picture looks good, it's plugged in all the way, and none of the Pins are sticking out as if one of the Latches in the Connector is broken. The connector that is plugged even halfway in will have enough of a contact to at least trigger a CEL, I don't see how the ECU Connector alone could be causing any of your issues.

As mentioned earlier, several places that professionally repair ECUs have their own fleet of Test Vehicles to replicate the issue to the fullest. In lieu of that, some places build or purchase Test Stands that would send Signals to the ECU and see how it would respond, like sending the Crank Sensor Signal and seeing if it will start outputting Injector or Spark Signals (though the latter can't provide the full picture), or at the very least it could be connected to a power supply to see if the Terminal responsible for the CEL would have power on it..

Hope this helps and best of luck!

Before I send off the ECU for a "Re-check", would a bad fuel pump ECU prevent the Main ECU from sending signal to the ignition system and fuel injectors and prevent them from functioning? From all that I have read on the fuel pump ECU by-pass, you can unplug the fuel pump ECU completely, connect the green and black wires, which turns on the fuel pump with the key in the run/start position and the vehicle will run just fine, the only purpose of the fuel pump ECU is to regulate the speed of the fuel pump as demand or lack of is requested. By the way, connecting the B+ and FP at the datalink connector does the same thing, the only difference is that the FP ECU is not dis-connected....

No, all the Fuel Pump ECU does is control the Fuel Pump, as written in the other thread on the subject, it's not even the ECU per say, just like with Igniter, in can only follow commands, it can't affect anything Upstream from it. Bridging B+ and FP Terminals is functionally the same as doing a full Bypass, just not nearly as tidy, here is a thread about it, you can try it, but unless the Fuel Pump ECU blows a Fuse every time it tries to turn the Fuel Pump On, it's not the culprit for your issues.

Hope this helps and best of luck!