Engine Check Engine Light Unless Scanner Attached


Dec 20, 2019
Hoping someone on the forum can help, this is a weird one. My 92 is throwing codes unless my scan tool is attached an on. When it throws codes they are for most of the sensors connected to terminal 46 on the EEC: TPS, ECT, ACT, etc. All of the sensors are new. The FI harness is new. The grounds are good. There is low voltage (~5.4) at two of the posts on the VIP port. The connector to the check engine light causes my Power Probe to beep intermittently but no voltage (or ground) indicated. Any ideas on what to check or test next? Could this be a bad EEC? Thank you!
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