Electronics question

[peterkottemann]

Does anyone know if I can use a second gen ECU inside a first gen car?

Just found out my caps leaked and blew the ISC through the back of the motherboard... I can fix a lot, but when you can see daylight though the circuit board, just write that one off...

[BaadVR4]

Short answer: no. They use different signals to determine crankshaft/camshaft position.

[mb3000]

If it's a 93 than it will use the separate cam & crank sensors like the 2nd gen.

[lawdogg]

Yes, you can use it, and it's super easy. You don't even need to do anything special. I am running my 94's ECU in my 92 after modifying only one wire. The 3 plugs just plug right in.

Ok so thanks to CoreyB to pointing this out ... you all might know this but I'm a little obtuse.

To make an adapter harness between a 1g and a hybrid ECU, the only thing you have to worry about is the little 12-pin plug. The other three plugs are for all intensive purposes directly complimentary.

See http://www.plxdevices.com/ECUDatabas...thTT_91_97.pdf.

Only 1 pin *needs* to go into the hyrid's 12-pin plug:

A quick run-through of the terminals off Stealth316 shows these pins are all in the 12-pin plug on the 94-95, and here's where they get their signal from on the 91-93:

Pin 59: A/C Switch 2
Pin 60: Rear heated o2 sensor, emissions (cali) - not present in 91-93
Pin 58: Engine Ignition Signal
Pin 52: Ignition Timing Adjustment Terminal

And come from these pins on the 91-93:

Pin 20: A/C Switch 2
Pin 101: Engine Ignition Signal
Pin 104: Ignition Timing Adjustment Terminal

In other words, if you want to run a 1g ECU on a 94-95, or a hybrid ECU in a 1g, you'll pretty much only have to deal with the Engine Ignition Signal and the 12-pin plug. SO there's no need to build a fancy adaptor harness unless you want to use it as a boomslang harness or something along those lines.

Thanks Corey!

To account for the different CAS sensor latency ... http://www.stealth316.com/2-cas_conversion.htm

[peterkottemann]

thanks law, it might be worth the trouble considering the price difference. I'll see if I can dig up a first gen at the same price though.

[x2xtreme360]

Keep in mind, you MUST use a fed spec in order for it to work. Cali spec cars had the 4 plugs like the OBDII cars.

[1993RT/TT]

Keep in mind, you MUST use a fed spec in order for it to work. Cali spec cars had the 4 plugs like the OBDII cars.

My 93 Cali spec turbo has 3 plugs. Hopefully you have a 91 or 92 they are easier to find

[x2xtreme360]

My 93 Cali spec turbo has 3 plugs. Hopefully you have a 91 or 92 they are easier to find

If this thread is about a VR4, an adapter harness would be needed. ALL Hybrid and OBDII turbo cars use a 4 plug harness (except for 98-99 which use a 3 row harness).

[lawdogg]

No no, this is what I'm saying. All 94-95, at least, hybrid ECUs have 4 plugs. The 3 plugs from 91-93 ECUs plug right in to 3 of those plugs. The fourth plug only needs one wire taken out of the 91-93 harness and connected.

To put the 94-95, fed or cali, into a 91-93 car .... simply plug all three plugs into the ECU. The remaining port, the little 4th plug, only needs one wire taken from the 91-93 harness and connected on its own, as I outlined above.

It absolutely works.