I have a 2004 TL with 67000 miles that is running well with no dashboard indicators of any type of problem with the car. I went in to an Acura dealer yesterday to get my California smog certificate and the car failed because their machine couldn't read my engine rpm through the car's test port. To check their machine, they brought over another TL and their machine worked so apparently something is wrong with my car. They now want $175 just to connect up to the OBDs to see if they get a code. I asked their chief mechanic what possible problems would cause this - car running well, no dashboard codes/lights but no rpm at the test port - and he didn't know. I'm thinking the only possibility might be a bad wiring harness from the OBDs to the test port. If some type of rpm sensor isn't operating, wouldn't the engine be running rough? I don't want to get involved in an expensive electrical hunt. Has anyone had a similar situation? Thanks in advance.

 

check fuse 7 and 21 to start under your dash. it may be that cluster. which is easy to swap but it may not be cheap.