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HoldenK
05-15-2021, 04:53 PM
i just bought a 1991 240sx coupe that has a S1 Rb25det, i've got the engine wiring down, I think.

My major questions is can I get the 240sx lights(head/tail, break and reverse lights) to work if i am on a haltech ECU controlling the Rb25? are the lights even affected by a new engine?

I've spent some serious time looking for how to make the s13 tach and speedo work with the rb25 and I haven't found anything. it you could refer me to some threads that would solve my issues or can explain it to me that would be much appreciated.

Thanks - Holden

Silv1401
05-15-2021, 11:56 PM
First off, you need to get over to nico and snag a virtual fsm for your car so you can just look at the wiring schematics. Second, your lights all run through a separate wiring harness. The ECU is an Engine Control Unit, and the wires from that only control powertain-related components. Lights, wipers, horn, blinkers, etc all run through a series of relays, switches, and fuses. So no, ecu is irrelevant for those items to function.

I can't help you with the speedo/tach wiring, however. Although, for the speedo, you can buy a little module to intercept the signal and correct it. essentially it's a little gain knob, so you can turn it up or down to increase/decrease the speed signal so that it's accurate on the dash.

Sent from my SM-N986U1 using Tapatalk

HoldenK
05-16-2021, 01:36 AM
First off, you need to get over to nico and snag a virtual fsm for your car so you can just look at the wiring schematics. Second, your lights all run through a separate wiring harness. The ECU is an Engine Control Unit, and the wires from that only control powertain-related components. Lights, wipers, horn, blinkers, etc all run through a series of relays, switches, and fuses. So no, ecu is irrelevant for those items to function.

I can't help you with the speedo/tach wiring, however. Although, for the speedo, you can buy a little module to intercept the signal and correct it. essentially it's a little gain knob, so you can turn it up or down to increase/decrease the speed signal so that it's accurate on the dash.

Sent from my SM-N986U1 using Tapatalk

its a wiring specialties harness they have everything labeled on there website luckily. thank you for explaining it is on a separate harness, thats something I was very confused on.

and I was able to find a module that is able to intercept both speed and tachometer so I should be set