Ok, Im looking for a keyed hot wire to connect my heated O2 sensor to...

I have read that most people splice it into the fuel pump wire...where is that located? and what color is it? so I can get this project done and over with...

thanks!

picture would be great!!


I have my hot wire coming from the O2 running by the drivers side firewall...it actually comes up right by the 3 relays...where the MAF is and stuff....if that helps!

 

Here's a diagram for ya bro. http://www.autozone.com/servlet/UiBr...3d80163fb5.jsp Amazingly quite informative. Tells you what wires are hot when and where and color too. Can't help with a pic though.

 

where is the fuel pump relay? is it one of those relay's on the firewall by the the MAF relay?

 

Yes, not sure which though.

 

Here you go.

 

What year is that, ringo? The fuel pump relay you're pointing to is the radiator fan relay on my '87.

You can pull a 12v ign on source from the EST or the 'fuel pump' relay. Just check which is hot with key on and not hot with key off.

 

It's an 89 TPI (dual fan). My 89 TBI (single fan) had it's relay there, but on dual fans it's between the radiator and battery.

 

they all look the same to me...I have changed them out over the years and Im pretty sure all the relays are the same part number? and I remember when I was trying to figure out my MAF relay a couple years back I switched the connections.

So which wire is hot when keyed? on those relays?

heres my 87

 

'So which wire is hot when keyed? on those relays?'

It's really best if you check for the hot wire with a meter. You'll need to verify it anyway. Just pull the connector off and test.

 

how? with a volt meter? just pull the relay off, stick the volt meter stem inside the relay on one of the wires and see if I get volts? and then see turn the key to on and test again? and which ever one I get volts when keyed...I can use that one for my heated O2 power?

 

Yes, just pull off the pigtail and test each wire going into the relay for 12 volts (or use a test lamp), key on then key off. The wire you want will probably be one of the smaller ones. The larger ones are going to be constant 12 or 12 out that the relay passes using the control (key on) voltage.

Even if I had two identical cars and KNEW which wire was which, I'd still confirm 12 volts with a meter. Anything can happen in 20 years to original wiring.

 

Well I found my fuel pump relay....its the one on the far right...I unpluged it and the pump never came on...There are 2 fat and 3 skinny wires...now I just gotta figure out which one is "key hot"

 

dang, so by that autozone diagram the cigarette lighter is always hot? i was hoping it was only on when in accessory