ECU Hold Power Issues when engine running

[All the gear no idea]

Hi All.

 

 Having an issue with my ECU hold power. If i power the car on without starting the engine, and turn off. The ecu power hold works fine and shuts off after the delay timer has finished. When the engines running and i shut it off, the IGN SW goes off, and can be seen going off, then a couple of seconds later the ECU detects it back on. But the key is now out of the ignition so has no voltage to it, so im unsure why it works when the engine isnt running, but not when the engine is running. Currently i am having to turn the IGN back on and off again after the car has stopped to get it to power down correctly.

 

Please see attached log.

 

Thanks Andy

 

 

Log 2024-03-3 6;29;12 pm - ECU hold power not working.zip

[Adamw]

There is no log in the zip file, just a windows shortcut link.  A log is probably not going to help much anyhow, you will need to trace the wiring to find out why there is still voltage on the Ign sw pin after you turned the ign sw off.  It must be coming from something else connected to that same ign switch circuit.

 

[All the gear no idea]

Hi Adam,

 

 So. i checked all the wiring, and when the IGN switch is switched off and the 12v drops out as you would expect. I did however unplug the Boost solnoid which is grounded through AUX 4 (fed off 12v ign sw live). When this is unplugged, the ecu shuts down fine from a running condition. When plugged in, the ecu doesnt power down using the ECU power hold function and displays IGN input on. But i have tested the voltage on the IGN live to the ecu upon power down, it is exactly the same voltage when the engine has been running vs when the ign has just been switched on and off (1.19V). So i am unsure of what to do next, as there isnt 12V on IGN SW even though the ecu is showing there is.

Also connected the boost solnoid back to 12v switch live. But pulled the wire on AUX 4 (boost control) out of the ecu and the ecu hold power works fine both engine running and not running.

Any thoughts on this?

Thanks Andy

[Vaughan]

Your ECU is being back-fed power through Aux 4, either connect the other side of the boost solenoid to an ign switched 12v source or use a spare Ign or Inj pin instead of Aux 4.

[All the gear no idea]

The boost solnoid currently is fed from a 12v ign switch feed. Which is what is so strange. The voltage doesnt differ and isnt 12v, but the ecu for some reason is registering it as so. I will try an inj or ign pin for the boost solnoid and see if that makes a difference.

[All the gear no idea]

This morning i have switched the boost solnoid to INJ 7. Seems to work fine now with no issues in both static and from an engine running perspective. 

Another issue i seem to have is when i first power the ECU up, it doesnt register an input on DI16. (I have a 3 position rotary traction switch on DI14,15,16) But if i rotate the switch to input on DI15 (when the cars powered up) it will then register active on DI15, and then i flick it back do DI16 it will also then show active. It just wont show it as active if it is being suppled 12v on that input from powerup. 

 

Anything im missing on that one?

 

Thanks

[All the gear no idea]

Edit to this - I had the switch routed from Di16+ to Di16-    

Im guessing that due to this configuration it is waiting for a pulse or change to activate it.

 

I have wired the switch to 12v live and fed back into the negative connection on the ecu (di16-) and it works fine and detects from a powerup situation.