Shortening Wires
The reason you should lengthen if necessary, the harness and not the 02 wires is the harness is copper wire that can be soldered. The 02 wire itself has a very high nickel content that the solder cannot adhere to for a good electrical connection. Bad soldering equals erratic signal to PCM and erratic fuel adjustments.
The reason you should lengthen if necessary, the harness and not the 02 wires is the harness is copper wire that can be soldered. The 02 wire itself has a very high nickel content that the solder cannot adhere to for a good electrical connection. Bad soldering equals erratic signal to PCM and erratic fuel adjustments.
BUT the reason you are not supposed to solder O2 sensor signal wires ANYWHERE, including the engine harness is because it will impede the air reference, leading to wrong readings. Nothing to do with how well they were soldered, or where they were soldered-Including if the terminal was crimped and soldered.
The air reference is drawn through the wire, soldering impedes the air from moving through the wire.
__________________
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People tend to overthink when talking about wiring. Lengthen or shorten whatever you need. Just know in 5v circuits to carefully work on them and make sure they are perfect. 5v circuits are more sensitive to resitance than a normal 12v circuit.
One for example is the TPS 1 and 2 circuits. Just do a good job and you wont have an issue
One for example is the TPS 1 and 2 circuits. Just do a good job and you wont have an issue
TECH Enthusiast
Joined: Sep 2014
Posts: 732
Likes: 1
From: alburnett, iowa
IM just getting done modifying a truck harness. I took the ecm plugs and got them to reach over to where they can go thru by heater box. Looks like after I get my motor/tranny thats on rebuilt subframe back to my 76 skylark I should have 8-10 inches of wire leads to put computor behind dash. A little over 1/2 the wires were fine, others like coil power I combined 2 to 1 lengthened & injectors combined driver side 4-1 same pass side then those 2-1 to computor. Cutting,soldering double shrinking tubing it. Plugged everything in let harness unravel, seem to workout ok then zip tie for now. Later after running I will put it in back in snake wrapping tube.
Cable Organizer is another good source for adhesive lined heat shrink, as well as split loom.
Tipsy
BUT the reason you are not supposed to solder O2 sensor signal wires ANYWHERE, including the engine harness is because it will impede the air reference, leading to wrong readings. Nothing to do with how well they were soldered, or where they were soldered-Including if the terminal was crimped and soldered.
If you do choose to change the length of O2 sensor wiring, it is MUCH easier to do it in the engine harness side, not on the sensor side of the harness, and as long as you use good practices to ensure a clean and proper signal conducts, you'll be fine.
If you choose to modify the length on the sensor side, you'll have to do so every time you replace a sensor (pain in the butt), and you'll need to use a very high heat and special silver solder, not the typical lead based stuff...if you do this, the sensor will work great without issues...but it's still a PITA when you need to do it again a few years down the road when you have a sensor that needs to be replaced.
I believe the wires used are so difficult to solder because they need to withstand EXTREME heat right where they connect to the sensor itself...no other sensor in a vehicle needs to withstand anything close to that level of heat.
Last edited by Mike454SS; Oct 6, 2014 at 12:24 PM.
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Here's a copy/paste of the GM Service information specific to heated oxygen sensor wire repairs:
Pay close attention to the meaning of Heated Oxygen Sensor Wiring Repairs, this means repairs to the sensor and wires, not the wire harness the sensor itself connects to.
And some more on high temperature wire repairs:
Having read that, I believe there is a bit of a misunderstanding on what this "air reference" means/does, so in an attempt to de-mystify the fact that this air reference is related to anything upstream of sensor and its connector:
http://<br /> http://www.carservice...r_06.18.11.png
However, since we are talking about critical engine sensors that provide the basis for many other systems, there is the possibility that these two aspects of the heated o2 circuits are being interpreted as inter-dependent or one in the same....
Performing a wire repair on any of these wires could result in one or more having a slightly different resistance (voltage drop) than another and when it comes to ensuring the ECM's signal out to the sensor is returned in the most accurate and non-offset manner, keeping these wires closely matched to one another and in an ideal condition is never a wasted precaution.
feel free to correct me if I'm incorrect in any of my statements.
Pay close attention to the meaning of Heated Oxygen Sensor Wiring Repairs, this means repairs to the sensor and wires, not the wire harness the sensor itself connects to.
Heated Oxygen Sensor Wiring Repairs
Caution: Do not solder repairs under any circumstances as this could result in the air reference being obstructed.
If the heated oxygen sensor pigtail wiring, connector, or terminal is damaged the entire oxygen sensor assembly must be replaced. Do not attempt to repair the wiring, connector, or terminals. In order for the sensor to function properly it must have a clean air reference. This clean air reference is obtained by way of the oxygen sensor signal and heater wires. Any attempt to repair the wires, connectors or terminals could result in the obstruction of the air reference and degrade oxygen sensor performance.
The following guidelines should be used when servicing the heated oxygen sensor:
•Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors. These materials may get into the sensor, causing poor performance. Also, the sensor pigtail and harness wires must not be damaged in such a way that the wires inside are exposed. This could provide a path for foreign materials to enter the sensor and cause performance problems.
•Neither the sensor nor vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks, etc., could block the reference air path through the lead wire.
•Do not remove or defeat the oxygen sensor ground wire (where applicable). Vehicles that utilize the ground wire sensor may rely on this ground as the only ground contact to the sensor. Removal of the ground wire will also cause poor engine performance.
•To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the vehicle harness connector.
Caution: Do not solder repairs under any circumstances as this could result in the air reference being obstructed.
If the heated oxygen sensor pigtail wiring, connector, or terminal is damaged the entire oxygen sensor assembly must be replaced. Do not attempt to repair the wiring, connector, or terminals. In order for the sensor to function properly it must have a clean air reference. This clean air reference is obtained by way of the oxygen sensor signal and heater wires. Any attempt to repair the wires, connectors or terminals could result in the obstruction of the air reference and degrade oxygen sensor performance.
The following guidelines should be used when servicing the heated oxygen sensor:
•Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors. These materials may get into the sensor, causing poor performance. Also, the sensor pigtail and harness wires must not be damaged in such a way that the wires inside are exposed. This could provide a path for foreign materials to enter the sensor and cause performance problems.
•Neither the sensor nor vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks, etc., could block the reference air path through the lead wire.
•Do not remove or defeat the oxygen sensor ground wire (where applicable). Vehicles that utilize the ground wire sensor may rely on this ground as the only ground contact to the sensor. Removal of the ground wire will also cause poor engine performance.
•To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the vehicle harness connector.
And some more on high temperature wire repairs:
High Temperature Wiring Repairs
Note: All wiring repairs need to be 200 mm from the heat zone. Areas of consideration would be any area located near the exhaust manifolds, catalytic converter, exhaust pipes, and turbocharged engines.
Items Required
•DuraSeal splice sleeves to crimp and seal connections
•High temperature SCT1 shrink tubing to protect the splice sleeves
•Terminated leads or pigtails
•The correct tools to remove the terminals from the connectors
Use high temperature bulk wire rated at 150°C (302°F) continuous temperature of the same or larger gauge size as the original wire when repair damage wire. Also replace any reflective tape that you remove during the repair.
High Temperature Wiring
Wiring that is exposed to high temperatures, 135°C (275°F) or higher, for prolonged periods of time may use materials i.e. wires, connectors, and shielding that has a higher heat rating than typical wiring. When making a repair in a high temperature area observe the following:
•Use high temperature bulk wire rated at 150°C (302°F) continuous temperature to replace any damaged wire.
•Replace any heat shielding that is removed.
•Cover any DuraSeal splice sleeves with SCT1 shrink tubing.
•After making a wiring repair, ensure that the location of the wiring is not moved closer to the heat source.
Identifying High Temperature Wiring
Note: High temperature areas would be areas located near exhaust manifolds, catalytic converters, exhaust pipes, and turbocharged engines.
Wiring that is exposed to high temperature, 135°C (275°F) or higher, for prolonged periods of time need special considerations when making wiring repairs. Areas that may be exposed to higher temperatures can be identified by heat resistant materials that are being used in those areas. These materials may include heat reflective tape, moon tape, and high temperature shrink tubing. Also conduit and other protective coverings may be used. Because conduit or similar coverings are used throughout the vehicle regardless of the temperature, it may be necessary for the technician to determine if an area is exposed to excessive heat before making a wiring repair.
Note: All wiring repairs need to be 200 mm from the heat zone. Areas of consideration would be any area located near the exhaust manifolds, catalytic converter, exhaust pipes, and turbocharged engines.
Items Required
•DuraSeal splice sleeves to crimp and seal connections
•High temperature SCT1 shrink tubing to protect the splice sleeves
•Terminated leads or pigtails
•The correct tools to remove the terminals from the connectors
Use high temperature bulk wire rated at 150°C (302°F) continuous temperature of the same or larger gauge size as the original wire when repair damage wire. Also replace any reflective tape that you remove during the repair.
High Temperature Wiring
Wiring that is exposed to high temperatures, 135°C (275°F) or higher, for prolonged periods of time may use materials i.e. wires, connectors, and shielding that has a higher heat rating than typical wiring. When making a repair in a high temperature area observe the following:
•Use high temperature bulk wire rated at 150°C (302°F) continuous temperature to replace any damaged wire.
•Replace any heat shielding that is removed.
•Cover any DuraSeal splice sleeves with SCT1 shrink tubing.
•After making a wiring repair, ensure that the location of the wiring is not moved closer to the heat source.
Identifying High Temperature Wiring
Note: High temperature areas would be areas located near exhaust manifolds, catalytic converters, exhaust pipes, and turbocharged engines.
Wiring that is exposed to high temperature, 135°C (275°F) or higher, for prolonged periods of time need special considerations when making wiring repairs. Areas that may be exposed to higher temperatures can be identified by heat resistant materials that are being used in those areas. These materials may include heat reflective tape, moon tape, and high temperature shrink tubing. Also conduit and other protective coverings may be used. Because conduit or similar coverings are used throughout the vehicle regardless of the temperature, it may be necessary for the technician to determine if an area is exposed to excessive heat before making a wiring repair.
http://<br /> http://www.carservice...r_06.18.11.png
However, since we are talking about critical engine sensors that provide the basis for many other systems, there is the possibility that these two aspects of the heated o2 circuits are being interpreted as inter-dependent or one in the same....
Performing a wire repair on any of these wires could result in one or more having a slightly different resistance (voltage drop) than another and when it comes to ensuring the ECM's signal out to the sensor is returned in the most accurate and non-offset manner, keeping these wires closely matched to one another and in an ideal condition is never a wasted precaution.
feel free to correct me if I'm incorrect in any of my statements.