I need wiring diagram for ksc-rz900s wiring diagram

Take a look at this manual diagram. https://www.manualslib.com/manual/359815/Kenwood-Ksc-Sw10.html?page=5#manual

Given the above is not your model, at least it shows the 10 pin. Ironically, below I offer a diagram of your model. The irony comes in the fact that the diagram appears labeled in Japanese But if you compare the two diagrams, maybe something will make sense from the one with the English labels. Otherwise, you might fire off a query to Kenwood customer support. https://www.manualscenter.com/manuals/kenwood/kscsw900-owner-manual.html
Here is a 10 pin harness compatible with the subwoofer. Kenwood Subwoofer Amp KSC Wa100 Wa80 Sw10 10 Pin Harness for sale online ' eBay

I don't have any information on how to power supply a kCSWA900 Kenwood subwoofer. However, I can tell you that the Kenwood KSC-SW10 compact powered subwoofer has a built-in amplifier with a 38 watts RMS power and a wired remote for control over volume level, variable low-pass crossover (50-120 Hz), and selectable phase control (0°, 180°) . The subwoofer comes with a power/ground wiring harness and preamp (RCA) and speaker-level inputs .

Please see this page:
KENWOOD KSC WA82RC Service Manual free download schematics eeprom...

You may need to wait a few minutes for the "Get Manual" link to appear below the preview picture.

Hello mikealtre,

Hopefully there's enough of the wires left to see their colors.

Here's a link to the manual. Other than the speaker level inputs, there's only 3 wires you need to be concerned with. Yellow is main power, black is ground, and blue is remote.

Hope this helps.

Never Use That Thing Again

Hello annieandstev,

The part number you want is E30-5462-38. It is available from: http://www.pacparts.com/. The cost is $43.66 plus shipping.

You may want to call their toll-free number and verify that the part is in stock: (800) 421-5080.

Hope this helps.

Hello Jax GS300,

Yes, you can use RCA cables. Just wire in a "low-level" converter.

Using RCA's is really the best way, allowing you to run shielded wiring to the sub, making it less likely that the wiring will pick up electrical interference. I'd install the converter on the rear speaker wires behind the dash.

If you do not want to convert the speaker output, you can drive the Kenwood directly from the speaker wires. The diagram in the install manual shows the connections coming off the rear speakers.

Here's a link to one output converter. This one will convert all 4 speakers.

http://www.crutchfield.com/p_142SLC4/Scosche-SLC4.html?search=level+converter

Hope this helps.

I had the same problem. Here is the picture i used.

i had the same problem Here is the diagram i used from someone else on fixya.  Thank you.

I had the same problem.  Here is the picture I used.  

Here is a picture to help you out.