Kjayden49

Hello, as stated in the title I have a 96 dx sedan that I just put a 99 ex engine and p2p ECU in, it also has an EM1 engine harness, I am wondering where the tach reading comes from as I have no rpm reading on my cluster, P.S. been told I’m supposed to have a wire coming from my dash for the dash harness, I DO NOT HAVE ONE. I have a friend who builds 1000hp B series and has toyed around a ton in eks he can’t find it either, if it helps it was made 11/95, but I was told it should come from dizzy, go to ECU, then go into dash ECU plug to the tach. It worked before the swap and no longer works. Please help!

JRCivic1

The '99 engine harness doesn't work in a '96 chassis... you need a '96-98 engine harness (preferably the same trim level as your chassis) and then either change any plugs necessary on the engine harness to fit the '99 engine OR install '96-98 parts where needed that match the engine harness, like the distributor.

This is common knowledge... and a guy who builds 1000HP Honda engines should absolutely know this.

Kjayden49

[QUOTE=JRCivic1;52842298]The '99 engine harness doesn't work in a '96 chassis... tbf everything works EXCEPT tach, fuel gauge, ECT, Speedo, just not tach…. Car runs pretty good too and only sensor not plugged in is upstream 02, so I’m gonna have you clarify, 99 harness does NOT work, or 99 harness prevents tach from working, assuming you state the latter, why? Also assuming you state the latter, could I not splice into the solid blue wire from the dizzy to run directly to tach then making it work?

spAdam

iTrader: (1)

JRCivic1 is correct. I think you have a different combination of parts than you think you have.

How many ecu connectors are on your engine loom? 99-00 (including EM1) only has two, not including the green C131 connector. The third connector lives on the main loom.

The pinouts are very different between 96-98 and 99-00 ecus. 96-98 do not have a C connector and 99-00 do not have a D-connector. You cannot mix and match and get the car to run, so if yours does then you've got something else going on.

99-00 engine looms do not have a tacho wire in them. The signal for the dash comes directly from the ecu via the main loom. 96-98 have a blue wire that runs from the distributor through the engine loom via the LH shock tower and to the dash, alongside the oil pressure switch, other dash outputs, and power for the injectors, ignition, and ecu. This is well known and documented, there's already another thread near the top of this forum where the fix is being discussed.

Post pictures of your ECU connections, including the end of the ecu itself.

JRCivic1

Based on your description of parts... your engine shouldn't even run. This means that some other wiring manipulations have occurred and it will be challenging for this forum to assist you. Assuming that what you say is correct, it would certainly be a worthwhile endeavor to connect your tachometer wire at the instrument cluster directly to the ICM wire... either at the ECU or at the distributor.