hmmm... you didn't check what colour it was to match your ecu first did ya
either you have a yellow plug harness trying to fit a grey plug ecu orrrrr you have a grey plug harness trying to fit a yellow plug ecu
or to make things more fun, you have an 89 grey plug trying to fit a 90+ or vice versa
what year is yours and what year is the engine & harness you have?