The Intake Manifold Runner Control (IMRC) is a system which uses dual intake runners to supply air to each cylinder. The secondary runners are normally closed, but the PCM opens them under high rpm conditions when the driver is demanding additional power from the engine. The IMRC system can be actuated using a single electric motor or dual vacuum motors. The IMRC system is functionally checked by monitoring the runner control plates using switches. If the actual position of the runner control plates does not match the commanded position, a malfunction of the IMRC system is indicated.

IMRC System Check Operation:
DTCs P1516 - IMRC input switch electrical check, Bank 1
P1517 - IMRC input switch electrical check, Bank 2
P1520 - IMRC output electrical check
P1518 - IMRC stuck open, electric operated
P1537 – IMRC stuck open, vacuum operated, Bank 1
P1538 – IMRC stuck open, vacuum operated, Bank 2

Monitor execution continuous
Monitor Sequence None
Sensors OK
Monitoring Duration 5 seconds
Typical IMRC functional check malfunction thresholds

IMRC plates do not match commanded position (functional)
IMRC switches open/shorted (electrical)