Firewall pass through
Thread Starter
Drifting
Joined: May 2007
Posts: 1,426
Likes: 165
From: Motor City
Firewall pass through
Currently in the process of wiring heated o2 sensors on the 93. I'm going to be running a relay off the battery, using the fuel pump relay for switched 12v power.
I've found the fuel pump relay under the passenger side dash but have no idea where I could run the switched 12v line from there back to the o2 sensor relay which is mounted by the battery.
Is there a easy firewall pass through?
I've found the fuel pump relay under the passenger side dash but have no idea where I could run the switched 12v line from there back to the o2 sensor relay which is mounted by the battery.
Is there a easy firewall pass through?
Race Director
Joined: Mar 2015
Posts: 15,926
Likes: 579
Currently in the process of wiring heated o2 sensors on the 93. I'm going to be running a relay off the battery, using the fuel pump relay for switched 12v power.
I've found the fuel pump relay under the passenger side dash but have no idea where I could run the switched 12v line from there back to the o2 sensor relay which is mounted by the battery.
Is there a easy firewall pass through?
I've found the fuel pump relay under the passenger side dash but have no idea where I could run the switched 12v line from there back to the o2 sensor relay which is mounted by the battery.
Is there a easy firewall pass through?
The hose is most likey old just cut by the switch stick a wire in it tape it up a bit of lube and pull it though. The cut the new hose in half longwise about six inches tape your wire and hose to the bailing wire lube it up and pull inside. Then cut the hose straight and put a connector back to the cut hose back to the brake switch..
Last edited by antfarmer2; Jun 4, 2015 at 09:41 AM.
Team Owner
Joined: Sep 2003
Posts: 25,413
Likes: 2,745
Currently in the process of wiring heated o2 sensors on the 93. I'm going to be running a relay off the battery, using the fuel pump relay for switched 12v power.
I've found the fuel pump relay under the passenger side dash but have no idea where I could run the switched 12v line from there back to the o2 sensor relay which is mounted by the battery.
Is there a easy firewall pass through?
I've found the fuel pump relay under the passenger side dash but have no idea where I could run the switched 12v line from there back to the o2 sensor relay which is mounted by the battery.
Is there a easy firewall pass through?
If you have a FSM look in book 2 in the 8A-201-XX where XX is pages and let the component locators in that section make your decision for you.
Actually with a later C4 with an under-hood fuse-block you might want to rethink the entire install. I'm quite sure a '93 has the under-hood box. You might try searching maybe for some other installs that mention how they accomplished it.
before posting!!
Last edited by WVZR-1; Jun 4, 2015 at 09:53 AM.
Race Director
Joined: Mar 2015
Posts: 15,926
Likes: 579
Inspect and decide for yourself but you might want to look in the vicinity of the vacuum line that goes from the SLS to the cruise module that is mounted near the ECM on top of the battery.
If you have a FSM look in book 2 in the 8A-201-XX where XX is pages and let the component locators in that section make your decision for you.
I hadn't seen your post before hitting the submit button. I had gone to check an appropriate FSM for the section the OP could use to check for himself. Had I seen it I would have likely hit the
before posting!!
If you have a FSM look in book 2 in the 8A-201-XX where XX is pages and let the component locators in that section make your decision for you.
I hadn't seen your post before hitting the submit button. I had gone to check an appropriate FSM for the section the OP could use to check for himself. Had I seen it I would have likely hit the
before posting!!
Thread Starter
Drifting
Joined: May 2007
Posts: 1,426
Likes: 165
From: Motor City
Inspect and decide for yourself but you might want to look in the vicinity of the vacuum line that goes from the SLS to the cruise module that is mounted near the ECM on top of the battery.
If you have a FSM look in book 2 in the 8A-201-XX where XX is pages and let the component locators in that section make your decision for you.
Actually with a later C4 with an under-hood fuse-block you might want to rethink the entire install. I'm quite sure a '93 has the under-hood box. You might try searching maybe for some other installs that mention how they accomplished it.
I hadn't seen your post before hitting the submit button. I had gone to check an appropriate FSM for the section the OP could use to check for himself. Had I seen it I would have likely hit the
before posting!!
If you have a FSM look in book 2 in the 8A-201-XX where XX is pages and let the component locators in that section make your decision for you.
Actually with a later C4 with an under-hood fuse-block you might want to rethink the entire install. I'm quite sure a '93 has the under-hood box. You might try searching maybe for some other installs that mention how they accomplished it.
I hadn't seen your post before hitting the submit button. I had gone to check an appropriate FSM for the section the OP could use to check for himself. Had I seen it I would have likely hit the
before posting!!
Thread Starter
Drifting
Joined: May 2007
Posts: 1,426
Likes: 165
From: Motor City
Ok, someone help me out. I found the underhand fuse block (x2). Busted out the old multimeter and every fuse had 12v to battery ground...so none of them are key on 12v?
I was thinking of using one of the underhood fuses as key on 12v to the new heated O2 relay. Maybe my thinking is wrong?
I was thinking of using one of the underhood fuses as key on 12v to the new heated O2 relay. Maybe my thinking is wrong?
Team Owner
Joined: Sep 2003
Posts: 25,413
Likes: 2,745
Ok, someone help me out. I found the underhand fuse block (x2). Busted out the old multimeter and every fuse had 12v to battery ground...so none of them are key on 12v?
I was thinking of using one of the underhood fuses as key on 12v to the new heated O2 relay. Maybe my thinking is wrong?
I was thinking of using one of the underhood fuses as key on 12v to the new heated O2 relay. Maybe my thinking is wrong?
Check the 8A wiring, 8A-200-XX images and the 8A-201-XX connector images to maybe determine just exactly how/where.
You could maybe use the UH box for the 12V B+ which would then of course "fuse" control the relay also. That is actually what the UH boxes do vs. a bunch of older fusible-links. Look at the fuel pump relay in the power distribution section for an example, I believe you might see the relationship of both the UH and IP fuse boxes. I don't have a '93 FSM but I believe that's what you'll see.
Thread Starter
Drifting
Joined: May 2007
Posts: 1,426
Likes: 165
From: Motor City
I checked a later FSM and it does seem that the under hood boxes aren't controlled BUT why couldn't you use a component under the hood that is already controlled? The AIR pump relay or maybe even the coolant fan relay? All are easily accessed and you could likely accomplish a splice or connector added to the wire chosen someplace closer to where you want to locate your relay, both are supplied power through the C100 connector at the firewall.
Check the 8A wiring, 8A-200-XX images and the 8A-201-XX connector images to maybe determine just exactly how/where.
You could maybe use the UH box for the 12V B+ which would then of course "fuse" control the relay also. That is actually what the UH boxes do vs. a bunch of older fusible-links. Look at the fuel pump relay in the power distribution section for an example, I believe you might see the relationship of both the UH and IP fuse boxes. I don't have a '93 FSM but I believe that's what you'll see.
Check the 8A wiring, 8A-200-XX images and the 8A-201-XX connector images to maybe determine just exactly how/where.
You could maybe use the UH box for the 12V B+ which would then of course "fuse" control the relay also. That is actually what the UH boxes do vs. a bunch of older fusible-links. Look at the fuel pump relay in the power distribution section for an example, I believe you might see the relationship of both the UH and IP fuse boxes. I don't have a '93 FSM but I believe that's what you'll see.
Also this way there is no fishing wires through the firewall.
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Team Owner
Joined: Sep 2003
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I think our heads are in the same place. Since I don't use the AIR pump, the wiring (and relay) are tied up out of the way. I'll use the AIR relay for key on 12v on my O2 relay. Then run a line from the battery with an inline fuse to power the new relay. I'll just have to make sure which terminal is key on 12v for the AIR pump relay or the coolant fan relay. Will that work?
Also this way there is no fishing wires through the firewall.
Also this way there is no fishing wires through the firewall.
Last edited by WVZR-1; Jun 5, 2015 at 11:00 AM.