I have a 1993 ford taurus 3.8L V6 automatic GL with 127,500 miles. I had a problem getting my car started last week and hooked up a ford OBD 1 digital code reader and got a 543 fault code. The 543 fault code definition read: fuel pump secondary circuit fault. What does this code mean? Someone told me it means my relay control module is going bad. Is this right?
It could be the fuel pump relay itself and/or the fuel pump. I’d start with the relay, and if that doesn’t get it, then the fuel pump. There are other possibilities, but those are the most likely two. (Sometimes a failing fuel pump can overload the relay and kill it too.)