1994 Chevy S-10 Is a relay necessary?

MITCHONE

MEMBER
1994 CHEVROLET S-10
6 CYL
2WD
MANUAL
330,000 MILES

I am converting a 1994 s10 to an Electric Vehicle. I have a problem with the tail stop lights. The stop light on the cab works. The white wire from the brake switch has power to the connector at the right side firewall, but there is no power coming to the relay on the firewall. The ground at the relay works. If I jump across the the white wire from the brake switch to the brown and white returning from the relay, the tail stop lights work. But they do not work if I feed current straight into the brown and white at the relay.
The other lights, park, signal, emergency flashers all work fine.

Question: can I by-pass the relay and connect the white to the brown and white at the connector inside the cab?

5 Replies

JMICHAEL8888

MECHANIC
45 POSTS

Someone may know a little more but the white wire goes to the cruise control module (brake input) and the brown/white wire I believe goes to a cruise control release switch on manuals. Both wires connecting to the brake switch to the module(cruise control).

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Saturday, December 27th, 2008 AT 5:21 PM

MITCHONE

MEMBER
6 POSTS

I do not have cruise control, and the repair manual shows the white wire going to the relay.
I can move the relay to the inside of the cab, but just can't figure out why the relay is necessary, unless as you said it has to do with the cruise control.

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Saturday, December 27th, 2008 AT 6:27 PM

JMICHAEL8888

MECHANIC
45 POSTS

Yeah I also see in the chilton manual where the white wire runs to turn/hazard switch also. The reason I said cruise control is the the brn/white wire is shown to only be used in cruise control. Just out of curiousity what and where is the relay your talking about?

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Saturday, December 27th, 2008 AT 8:03 PM

MITCHONE

MEMBER
6 POSTS

By the way, thanks for your interest. The relay is on the firewall in the engine compartment. I believe that there is a bad connection somewhere between the inside of the firewall and the outside, as the brake light will sometimes work. I can see no reason not to move the relay to the inside of the cab, but also can not see a reason for the relay. The relay is not shown in my Haynes manual, but is there in the online eautorepair from Mitchell auto repair. I have found the Mitchell information fits my S10 much more closely than the Haynes.
Anyway, I haven't seen anybody jumping up and shouting "don't do it" so I think on another warm day I will move the relay into the cab. Interesting though, isn't it?

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Sunday, December 28th, 2008 AT 10:25 AM

JMICHAEL8888

MECHANIC
45 POSTS

That is very interesting. The reason I asked about the relay is because I didnt see it. Some of the manuals are so limited anyway as in abs wiring or even a/c wiring.
You were talking about bypassing the relay. Some relays control voltage but I bet that one is a protection relay. I would as you said at least move it in the cab before bypassing it.
Sorry I cant be of any more assistance, like I said my manual has the brn/whit wire going from the cruise control module to the cruise control release switch and it says the brn/white wire changes to purple after the switch. Then going to electronic brake control module and brake switch.