No-Crank Click Then No-Start After CPS Rebuild - Bad ECU Grounds and Starter Signal Wire

Electricalintermediate✓ OP Confirmed

Problem

After reinstalling a rebuilt CPS, the car would only click when turning the key and would not crank. Once the cranking issue was resolved by bypassing the starter signal wire, the car cranked but would not start - no tach movement and no spark, indicating the CPS signal was not reaching the ECU.

Single click from passenger side kick panel area when turning key to startStarter solenoid clicks but engine does not crankAfter bypassing starter signal wire: engine cranks but will not fireNo tachometer movement while crankingNo flashes from timing light while crankingCar previously died when glove box was closed hard (intermittent ground issue)

Root Cause

Two issues: (1) High resistance in the original starter relay signal wire prevented enough current to fully engage the starter solenoid. (2) ECU ground wires were bolted to badly corroded/rusty metal behind the glove box, creating a poor ground connection that prevented the CPS signal from reaching the ECU. The bad grounds explained why the car had previously died when the glove box was slammed shut (vibration momentarily breaking the weak ground connection).

Confidence

Moderate confidence — Original poster confirmed this resolved the issue

View Original Thread →Posted May 2022 on SupraForums.com