Two separate inputs
GM's 1993 ECM wiring identifies distinct high- and low-resolution distributor circuits. A failure can be in the sensor assembly, wiring, connector, power/ground or ECM-side circuit.
LT1 · 1993 · DISTRIBUTOR REFERENCE
1993 LT1 Distributor Reference Signals
The distributor is not one yes/no component. The ECM uses distinct reference information and the circuits must be isolated before replacement.
APPLICATION: 1993 Firebird / Formula / Trans Am 5.7L VIN P LT1 only.
Revised DTC 36 chart
GM Bulletin 316528 replaced the original 1993 F-body DTC 36 chart. The bulletin defines DTC 36 around faulty high-resolution information or an extra low-resolution pulse, so the revised chart—not an owner-forum shortcut—controls diagnosis.
DO NOT REPLACE YET
Prove the circuit first
Verify exact-year feeds, grounds, reference circuits and waveform behavior before condemning the distributor. Wiring faults can mimic an internal Opti failure.
How FPV uses the signal information
- Start with the symptom and DTC combination, not a distributor purchase.
- Determine whether spark, injector operation or both disappear.
- Use the revised 1993 chart to isolate high-resolution, low-resolution and ignition-control branches.
- Inspect connector/harness condition, especially after distributor or water-pump-area service.
- Only replace the distributor when its branch is proven and the external circuits pass.
AFTER THE FAILURE IS PROVEN
Use the proven failed branch—not the original symptom—to choose the replacement. Go from diagnosis to the Parts Verdict →