I have a 1996 civic and the connecting pipe rusted out so we had to replace it also the thermostat housing. We noticed a ground with 3 wires connecting to it but we didnt know it at that time so we cut it. The new housing that we got didnt have any grounding terminal so we didnt put it back yet. Then we had another problem which was crank no start with CEL light on. We tried grounding those 3 wires together and spliced it into a single wire then to ground and the car started. But the CEL light is still solid. Also when i turn it to ON(II) position, the cel light will flicker just as the main relay clicks the stays solid again. I tried jumping the service connector hoping to get some codes but it still solid. Please help me i’m getting confused! Thanks!

 

Those wires ground most of the ECU system, so they are important. Sometimes the thermostat cover and/or housing is not solidly grounded to the engine. With the key on, there should be less than 0.1 volts from the wires to the battery (-) post. If there is a significant voltage, find out where the problem in the grounding system is by measuring from each point, moving closer to the battery.

 

Car is running fine now. But the only problem is now i got a solid CEL light. Before it was not there when i was using the old thermostat housing. Any ideas where it is coming from? Is a bad ground causing this?

 

Without knowing the code it's throwing any responses here will be pure guesswork. It's a '96 so it's OBD-II, take it to your local parts store and get the codes read (most Autozones and the like will do it for free) and report back.