Tweak'd Wiring Harness Routing Issue - Coolant Temp Sensors Swapped on 7MGTE

Electricalintermediate✓ OP Confirmed

Problem

After installing a Tweak'd aftermarket wiring harness on a 7M-GTE, the harness could not be properly routed because sensor plugs would not reach their intended connections. Specifically, the cold start coolant temp sensor plug and ECU coolant temp sensor plug appeared too short or misrouted to reach the correct sensors on the thermostat housing area.

Wiring harness sensor plugs not reaching their intended connectionsCold start coolant temp sensor plug routing did not make sense with sensor placementUnable to reinstall power steering fluid reservoir due to harness misroutingHarness appeared to route down and back up unnecessarily instead of exiting near the cam covers

Root Cause

The coolant temperature sensors on the thermostat housing were installed in each other's positions. The cold start injector coolant temp sensor was in the lower thermostat housing spot when it should have been in the upper spot on the head water outlet housing near the cam covers, and vice versa. What appeared to be 'unique sizes' preventing swapping was actually galling of the aluminum threads, not different thread sizes. With the sensors swapped to their correct positions, the harness routing made sense and plugs could reach their intended sensors.

Confidence

Moderate confidence — Original poster confirmed this resolved the issue

View Original Thread →Posted July 2021 on SupraForums.com