My 89 22re is having some timing problems I first noticed when I went to smog it and it failed due to 28btdc (see 89 timing problem). I jumped the test plug and found two codes. 12 and 51. My Haynes book tells me that 12 "RPM signal" Diagnosis "no Ne and G signal to ECU within 2 seconds after the engine is cranked Trouble area: "Distributor, Distributor circuit, Starter signal circuit, or ECU. The Second code is 51, and my book doesn't show a 51. Are there any techs reading this that could point me in the right direction to properly diagnose these problems?