Swapping ECU, UCH and Transponder Ring - Won't fire, alarm now disarmed.

[adamlstr]

So, having only one key I bought an ECU, UCH, 2 Fobs and Transponder Ring.

I disconnected the battery, removed each part and connected their replacements.

I put the key to Pos. II, all the right lights went off / stayed on.

I tried to start and it just went dead. No clicking, no turning over, just dead. Not one light on the dash on any position.

I plugged my original stuff back in and I'm back running again, only without my alarm. The central locking works fine, but I can lock the car with the fob, unlock the door with the key and start the car without the alarm going off.

What have I broken? :dead:

Is there a set procedure for replacing this stuff, or have I been sent dead components?

 

[adamlstr]

Any of the traders around this Monday morning to answer this?

Strangely, on Sunday I had my alarm back. But I think the battery is draining very quickly.

If I leave it longer than 3-4 hours, it won't start.

 

[MicKPM]

Are you sure everything was plugged in correctly?

 

[adamlstr]

Yeah, the plugs only really go in one way.

The only thing I was doubtful of was the ECU, I plugged that in but just rest it on top of the original. Does that need a decent mount for its earth?

 

[mark123]

I've done similar and it worked no problems on a 172 cup. The new parts are from a 172 cup I assume?

Try bolting the ecu back in to its mounting.

 

[adamlstr]

I've done similar and it worked no problems on a 172 cup. The new parts are from a 172 cup I assume?

Try bolting the ecu back in to its mounting.

I believe they're all from a 172 Cup yes, that's how they were sold to me.

However, the non-starting issue did come back yesterday with all my original bits still on. I'm pretty sure the battery is the cause of all this.

Whether the battery is failing by itself or whether something is draining it is my next issue.

 

[MicKPM]

The ECU earths via the engine loom not the ECU chassis so it won't make any difference if it is bolted down or not. It does sound like a poor battery/earth issue but it's curious that it wouldn't work when he swapped the setups but when he swapped back it fired... nothing was done to the battery/earth connections I assume?

 

[adamlstr]

nothing was done to the battery/earth connections I assume?

Nothing other than disconnecting it while swapping the components!

 

[MicKPM]

I'd try it again to see if you get power and if not have a good pull on the cables to see if it kicks in to life.

 

[adamlstr]

Turns out this was a buggered battery. Will hopefully get all the gubbins swapped over now.

That'll teach me for not checking the basics first! Oddly, the battery wasn't giving any symptoms and was showing 12.8V.