Quick ? with LM-1 wideband
Thread Starter
Melting Slicks
Joined: Jan 2005
Posts: 2,658
Likes: 4
From: Clifton Park NY
Quick ? with LM-1 wideband
So I'm hooking this up and I want it to be permanent. In the directions it talks about wiring it to the starter solenoid. I understand why but my question is can't I just wire it to 12volts that turns on when the key is in the run position? Such as the 12 volts that feeds the ecm?
Race Director
Joined: Apr 2003
Posts: 17,700
Likes: 1,667
From: moraga ca
I've had my LM1 for over 3 years and found it to be invalualble. Mine is not hardwired. I would think if it is wired to the starter solenoid, power would be cut off after the motor is started. The hot when in run wire would be better. Might want to give them a call. Good luck
Le Mans Master
Joined: Aug 2000
Posts: 8,838
Likes: 31
From: Australia
It recommends a relay on the solenoid circut ; not to the solenoid itself.
From LM-1 manual
"It is NOT a good idea to connect the LM-1 permanently to 12V and switch it on before the vehicle is started. Condensation water can form in the exhaust pipes.
This condensation water could then be blown by the exhaust stream against the hot sensor when the car is started. The resulting heat shock can permanently damage the sensor.
To protect the LM-1 when installed permanently it is a good idea to power the LM-1 only after the car is started. The starter motor in some vehicles can create voltage spikes of over 100V that have the potential to do damage.
A relay connected as shown insures that the LM-1 is disconnected while cranking. This reduces further drain on the car battery by the sensor heater and protects the LM-1 against abnormally large voltage spikes."
From LM-1 manual
"It is NOT a good idea to connect the LM-1 permanently to 12V and switch it on before the vehicle is started. Condensation water can form in the exhaust pipes.
This condensation water could then be blown by the exhaust stream against the hot sensor when the car is started. The resulting heat shock can permanently damage the sensor.
To protect the LM-1 when installed permanently it is a good idea to power the LM-1 only after the car is started. The starter motor in some vehicles can create voltage spikes of over 100V that have the potential to do damage.
A relay connected as shown insures that the LM-1 is disconnected while cranking. This reduces further drain on the car battery by the sensor heater and protects the LM-1 against abnormally large voltage spikes."
Thread Starter
Melting Slicks
Joined: Jan 2005
Posts: 2,658
Likes: 4
From: Clifton Park NY
Maybe I'm just gonna have to suck it up. Maybe I can just still run it off the A/C circuit but just set it up with a relay or time delay of sorts so it doesn't turn right away. Giving it a moment before its powered.
Thread Starter
Melting Slicks
Joined: Jan 2005
Posts: 2,658
Likes: 4
From: Clifton Park NY
ok, so I'm gonna use the relay to hook up. Gonna go to the (+) 12 volt side of solenoid of the starter. So I understand this correctly I can just go to the solenoid circut not to the actual location of the solenoid?
Le Mans Master
Joined: Aug 2000
Posts: 8,838
Likes: 31
From: Australia
from install manual
"A relay connected as shown insures that the LM-1 is disconnected while cranking"
You wire the O2 from a switched 12V supply through a relay that is normally closed .You operate the relay from the starter solenoid circuit (as you say anywhere on the circut) so than when you crank engine over ,the relay operates and kills the O2.
Once the engine fires, power to the relay is off and the O2 is powered up again
Thread Starter
Melting Slicks
Joined: Jan 2005
Posts: 2,658
Likes: 4
From: Clifton Park NY
Thanks
I finally figured it out. I am wiring off the starter relay. For others that might be doing this heres some info.
Just for information in case anyone comes across this thread in a search looking for detailed information on wiring one of these up on an early C4.
Took me an hour to find the Starter Interupt Relay.
Location- Just behind the command center. It has 4 larger sizes wires on it (3 Green/1 Purple) Relay and bracket are off white color
The relay I used for the LM-1 was picked up at advance auto
BWD-R310741-5132 cost is $11.29
You'll also need red colored insulated spade lugs and a means of connecting into the purple wire on the starter interupt relay.
I finally figured it out. I am wiring off the starter relay. For others that might be doing this heres some info.
Just for information in case anyone comes across this thread in a search looking for detailed information on wiring one of these up on an early C4.
Took me an hour to find the Starter Interupt Relay.
Location- Just behind the command center. It has 4 larger sizes wires on it (3 Green/1 Purple) Relay and bracket are off white color
The relay I used for the LM-1 was picked up at advance auto
BWD-R310741-5132 cost is $11.29
You'll also need red colored insulated spade lugs and a means of connecting into the purple wire on the starter interupt relay.
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