K-Series Swap Getting Working Speedometer with CSS Transmissions

Some early (02-04) K-series transmissions use a vehicle speed sensor (VSS) driven off of the differential. This is just like all older Hondas and you can feed these VSS pulses directly to your 88-91 Prelude cluster. The speedometer will work as intended like this.

NOTE: Don't be fooled by transmissions with a plug in the VSS hole, there is no VSS drive gear on the differential so you can't just drop in a VSS:

Most K-series transmissions utilize a countershaft speed sensor (CSS) on the front of the transmission to generate the speed pulses. Unfortunately CSS pulses much more for a given wheel speed than VSS, which means feeding the CSS signal to your speedo will peg it almost immediately.

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88-89 PRELUDE IMPORTANT INFO:

88-89 Prelude clusters require a physical cable running into them to have a working odometer. You will have to use a VSS K-series transmission for this. See our blog post here for more info: K-Series Swap 88-89 Speedometer Connection

If you don't care about the odometer working then the rest of this blog post is still applicable to 88-89 Preludes and will result in a working speedometer.

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In order to have a working speedo while using a CSS transmission there are 4 steps required:

Step 1 - CSS to VSS Connector Adaption:

You must adapt the older style VSS connector on your harness to the CSS style. We can supply the K-Swap VSS to CSS Adapter, which also includes a jumper wire used in step 3 below:

Prelude Engineering K-Swap VSS to CSS Adapter

Here it is installed:

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STEP 2 - Convert the CSS Pulses to VSS:

There are two main options to do this, we prefer the first:

CSS TO VSS BEST OPTION:
The easiest, cleanest, and cheapest option is to have your KPro v4 equipped ECU modified to output the old style VSS pulses on ECU pin B11.

If you haven't ordered your KPro v4 yet then you should definitely ask your dealer/installer to do this modification at time of ordering.

This is how we do it on our swaps. If you already have a KPro v4 ECU it's possible it already has this modification, check the circuit board:

If your ECU does not have this modification then you could send it back to your installer/dealer to have it done. If you don't have an installer then we recommend HAMotorsports, shoot them an email. This modification involves micro soldering and is not a DIY friendly mod, unless you are experienced soldering at this scale.

ALTERNATIVE OPTION:

If you have an older KPro that doesn't support the mod then an alternative is to wire in an external converter to change the CSS pulses to VSS.

There are a few products out there that can do this, here is the "K-Tuned All-In-One VSS Converter" for example:

STEP 3 - FEED NEW VSS WIRE TO C101 CONNECTOR:

At the ECU connectors install the B11 to C101  jumper wire that we supplied with our VSS to CSS adapter.

STEP 4 - CHANGE KPRO SETTINGS:

The final step is changing your KPRO settings with KManager so that your KPRO outputs the VSS signal on the ECU B11 pin: 

This post is just an overview. Please see our K-Swap VSS to CSS Adapter installation instructions for all the install and configuration details.