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Author Topic: S12 CA18ET to CA18DET swap question  (Read 66 times)

Offline XortioN

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S12 CA18ET to CA18DET swap question
« on: 09:20:20 AM / 14-Jan-19 »
So long story short, I swapped my engine for an S13 CA18DET coming from an s12 CA18ET.

I removed the S12 loom going on the driver side (LHD car) from the ECU to the connectors in the engine bay near the MAF. I used the complete S13 engine loom and wired all the needed wires to provide 12v const and earth to the S13 ECU.

Then I used a relais to give switched 12v to all the ignition on 12v needed for the S13 ECU. For this ignition on signal I tapped of directly from the ignition switch, more specific the black/white wire. This seems to give ignition on signal, but when the engine is running and I turn off the ignition switch it still gives me 12V (when engine is not running, it switches correctly).

So for some reason my ignition switch only switches correctly when the engine is turned off.. As if the ignition on wire of the S12 loom is getting 12v somewhere once the engine is running. Anyone has an idea where to look??? I left the S12 wiring alone, so I'm pretty mind blown and have overlooked my own wiring for several times. Plus it wouldn't make sense that my S13 wiring would be the cause since it doesn't "send" power to the S12 loom.

The only thing I can think if is that there is a bad ground somewhere where the old plugs of the stock S12 loom meet up in the engine bay?
« Last Edit: 09:21:13 AM / 14-Jan-19 by XortioN »

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Offline JonB

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Re: S12 CA18ET to CA18DET swap question
« Reply #1 on: 07:53:49 PM / 14-Jan-19 »
You really need an fsm.

But if i remember correctly, that black and white wire is hot all then time, and its supposed to be. If i remember correctly, thats the hot coil wire

Offline kelso840

Re: S12 CA18ET to CA18DET swap question
« Reply #2 on: 07:46:27 AM / 15-Jan-19 »
You really need an fsm.

But if i remember correctly, that black and white wire is hot all then time, and its supposed to be. If i remember correctly, thats the hot coil wire

Yeah, I seem to recall the Start Signal wire being orange. I believe there's PDF versions of the s12 tech manuals somewhere on this site. Use the custom search in the top right corner to find a wiring diagram so you know what s12 wires you're working with.
Infrequently driving an s12.

Offline XortioN

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Re: S12 CA18ET to CA18DET swap question
« Reply #3 on: 09:29:30 AM / 16-Jan-19 »
The orange is the start-signal with the CA18DET ecu, that's correct and that's wired up to the black/yellow from the S12 ignition switch. This way the S13 ECU knows when the engine is cranking. But I'm looking for a signal that stays 12V as long as the key is in the 'on position' and goes 0v when turned off.

From what I can tell on page EF-12 and EF-13, the B/W wire should be ignition on.

The Black/White wire on the S12 ignition switch gives 12V when the ignition is turned on and 0v when in off position (S13 ECU turns on fuel pump primes for 5sec like it should en stops when turning key in off position). UNLESS the engine is running, then for some reason it stays 12v even with the key out of the contact.
« Last Edit: 10:22:02 AM / 16-Jan-19 by XortioN »

Offline XortioN

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Re: S12 CA18ET to CA18DET swap question
« Reply #4 on: 09:45:04 AM / 17-Jan-19 »
« Last Edit: 09:46:11 AM / 17-Jan-19 by XortioN »