connector C105 question, 98 vs 99+

[slow]

I found these pinouts for the 98 cars.

c105 8 pin black
a-ppl/wht tcs indicator lamp output failure
b-pnk-fuse output ign
c-brn/wht-tcs switch signal
d-dk grn- cruise control signal disengage
e-not used
f-wht-cruise control indicator lamp output
g-wht-tach signal
h-ppl-air reaction solenoid relay output coil

today, i was installing a n20 setup on a 2000 Ws6 formula, and the car already had a tach splice into the #10 PCM pin, so i took a volt meter, and tested for continuty between the C105 white wire, and the #10 pin, and it was connected.

The weird part was the 2000 C105 connector, had 5 wires on the PCM side, and only 4 on the Vehicle Side. (male) With the tach wire being unused. I used a packard metripack pin, and slid it into the unused space, for a clean no hack job splice.

The question i have is, WHY was the one side of this connector not used by GM, and why did they bring a tach signal to the connector? It seemed almost too easy that im suprised nobody has done this in the past 4 years.

Anyhelp would be appreciated. And if this method ends up working fine, i'll be happy to supply people with wire, and the pin for a no splice tach splice.

I know on my 98, both wires are used, so i could not do it on the 98, but anybody know if all 99+'s are unused? or just on certain models

Thanks

Ryan

[slow]

answer.

The TCS/ASR system needs a tach signal, so all the cars get the extra tach signal going to this connector. The car i installed the n20 on yesterday, did not have TCS, so that is why the harness is open.

So, what this means, if you don't have TCS/ASR but need a tach signal, there is a white wire in the C105 (8 pin black connector) that has the signal, so no need to splice at the comptuer, or even splice into the factory harness at all

if you have TCS, you will want to get a male and female version of that connector, to make a plug in play tach splice, if you do not, you simply need a single metripack pin and weather seal. PM me if you need a source for these parts.

[smiley]

good info! thanks!