11-06-2017, 04:05 PM
It took me a while to figure this all out.
The Allison ECU is mounted in the compartment just ahead of the entry door. It is mounted in the back of the compartment with a vertical stack of five relays and three circuit breakers above the relays.
The relays are assigned functions as follows, starting from the top relay and working down.
Neutral Start - this relay prevents the starter from engaging unless in neutral
Reverse Signal - connects to a relay to control the backup lights and reverse alarm if so equiped.
Check Trans light - this normally closed relay controls the light on the dash.
ECU Power - this relay turns on power to the ECU and Check Trans light when there is engine oil pressure. A wire runs from a circuit breaker above the relays to the rear of the engine to the oil pressure switch and then returns to this relay.
ECU Power - this relay controls power to the ECU based upon ignition switch position
The Allison ECU is mounted in the compartment just ahead of the entry door. It is mounted in the back of the compartment with a vertical stack of five relays and three circuit breakers above the relays.
The relays are assigned functions as follows, starting from the top relay and working down.
Neutral Start - this relay prevents the starter from engaging unless in neutral
Reverse Signal - connects to a relay to control the backup lights and reverse alarm if so equiped.
Check Trans light - this normally closed relay controls the light on the dash.
ECU Power - this relay turns on power to the ECU and Check Trans light when there is engine oil pressure. A wire runs from a circuit breaker above the relays to the rear of the engine to the oil pressure switch and then returns to this relay.
ECU Power - this relay controls power to the ECU based upon ignition switch position
Jon Kabbe
1993 coach 337 with Civic towed