Ok first and foremost I did search the information was pretty vague. I have a 92 SC4 would like to have a definite answer on how to bleed the trac and the abs. I figured since I was doing my brake lines today, I should go ahead and bleed the trac and abs out too.
bleeding abs and trac system?
- Thread starter ihiryu
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The 1UZFE EGR Delete Kit is available for sale here.
The top connection (pin 1) of the three connections should be connected to NEGATIVE, and the bottom connection (pin 3) should be connected to POSITIVE.
The type mentioned in post 2 above is with regard to a 1994 Supra MkIV and that version of TRAC incorporates the rear brakes into the system, therefore there is the need to occasionally replace and bleed the TRAC system.
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I don't know how similar the SC's TRAC is to the MKIV Supra, but I'm assuming it's pretty similar if there's a separate TRAC pump, etc.?
Following is a procedure we use for the Supra (originally written by Dave Ruder back in 2000 or before).
I used this procedure for my Supra, (before I removed my TRAC system completely) and it worked a treat . The TRAC pump ejected probably 3-4 ounces of the filthiest brake fluid I'd ever seen, so I think it was well worth doing.
"Some people have emailed me wanting trac bleeding intructions. While it really isn't absolutely necessary to bleed the trac system, it is the only way to change the fluid that is trapped in the trac pump and the trac control valves. As brake fluid absorbs water, it accelerates the corrosion process on all the metal parts in the brake system, including the trac parts, so it's not a bad idea to change the fluid occasionally to prevent future problems. Also, if you EVER let the reservoir run dry, like if you pull the calipers and let the fluid drain out of the lines, you probably introduced air to the trac system and should bleed it if you want it to function exactly as it was designed.
The manual calls for a special tool to do the procedure. I've traced the wiring paths, and 'made' this special tool, which is nothing more than a couple wires with appropriate connectors on the ends.
One last thing. Others have mentioned that the trac pump can be operated simply by 'jumping' the relay in the passenger side of the engine compartment, but I'm convinced that this will lead to incomplete bleeding of the trac system. The instructions in the manual ask that the ignition switch be turned to ON while the trac pump is operating, and I've discovered why this is recommended. I've spoken personally to one of the engineers that DESIGNED the ABS system for the mkIII and mkIV thunderbirds, and he informed me that when the ign switch is turned to 'on', the system performs a self test where it energizes all the solenoid valves one at a time and runs a self diagnosis. If the trac pump is operating and the bleeder nipple is open when the 'self check' is performed, any air bubbles trapped against the ABS or TRAC valves will be allowed to escape. This is the only way to get rid of these air bubbles. If air bubbles are present in the trac or ABS system, it won't make the car 'undrivable', and it may not be obvious in how the ABS and TRAC systems operate, but without a doubt the systems will function better with zero air in the system.
So, if you want to bleed the trac system, or change ALL the fluid, here is how to do it on a 1994 MKIV Supra.
1) Make a 'jumper' wire by attaching appropriate ends on two 4 foot wires that will allow you to attach the wires to the + and - on the battery, and will also allow you to attach the other ends to the male prongs in the trac pump connector. The ends you'll need to attach to the jumper wire are female, and are in the shape of a slot. These can be purchased at an auto parts store, or radio shack The wires should slip onto the appropriate prongs inside the trac pump connector, and SHOULD NOT BE ALLOWED TO TOUCH EACH OTHER, or you will have a direct short and that will MELT your jumper wire and possibly cause a fire.
2) Identify the trac pump connector. It is directly in front of the brake master cylinder. Seperate the 1/2's of the connector by squeezing the retainer and pulling the 1/2 nearest the driver's fender toward the driver's fender. After you have pulled the driver's side 1/2 of the connector off, that side will hang free, while the side nearest the passenger will remain attached to a bracket. It is the side nearer the passenger that remains attached to a bracket that you will attach the jumper wires to. You will see three prongs inside the connector, and three wires exiting the back of the connector. The TOP wire is solid blue. The middle wire is yellow. The BOTTOM wire is black or dark green (I'm colorblind, sorry). The wire colors are DIFFERENT on the now free hanging connector nearer the driver's fender. The TOP wire is Blue with a yellow stripe, the middle wire is white with a green stripe and the BOTTOM wire is White with a black stripe.
3) Carefully attach one wire to the top prong in the connector that is attached to the bracket. This prong corresponds to the solid blue wire.
4) Carefully attach the other END of this same wire to the positive terminal of the battery.
5) Carefully attach one end of the OTHER wire to the bottom terminal of the connector attached to the bracket that corresponds to the solid BLACK wire. THE WIRES MUST NOT TOUCH EACH OTHER, AND THEY SHOULDN'T TOUCH THE MIDDLE TERMINAL. THEY SHOULD ONLY TOUCH THE APPROPRIATE POST IN THE CONNECTOR.
6) Briefly attach the other end of this last wire to a metal part of the chassis that is well grounded, like the nuts on the driver's shock tower. THE PUMP SHOULD OPERATE. Don't make this last connection to the negative terminal of the battery, as the spark created may cause an explosion. REMOVE the wire from the shock tower nut to stop the pump now, and hang it somewhere where it won't contact a ground point and operate the pump.
7) Locate the bleeder nipple for the Trac Actuator, located between the master cylinder and the driver's fender. Remove the little rubber cap on the nipple, and attach a hose to the nipple. Loosen the nipple so the fluid can escape, and be prepared to catch the fluid in a jar or cup and don't let it contact your paint.
8) The trac pump should NOT be operating right now.
9) Start the car's engine
10) Attach the last wire to the shock tower to start the pump operating.
11) LET THE PUMP OPERATE for 60 seconds before tightening the bleeder nipple. Don't open the nipple too far or the fluid will pump out too fast and you'll run out. There must be adequate fluid in the reservoir, and the reservoir can run dry in one of its three compartments while there is plenty of fluid in the other two. The reservoir is divided front to back into three compartments below the LOW Line, so WATCH CAREFULLY, and if it is draining too fast, close the bleeder nipple a little to slow the process. Fluid should be pumping through your attached hose and into the cup at the open end of the hose.
12) After you tighten the bleeder nipple all the way to stop the fluid from escaping, you must let the trac pump operate for an additional 30 seconds.
13) Remove your jumper wires and stop the pump.
14) Shut off the car. Clear the trouble codes by resetting the ECU. The procedure is supposed to trip a code.
The trac bleeding should be done AFTER all calipers are bled.
NOTE: If you look really closely on page BR-11 in the manual, you'll see a picture of a jumper wire connecting the battery and the trac pump connector. IT APPEARS IN THIS PICTURE THAT THE + TERMNIAL OF THE BATTERY IS CONNECTED TO THE BOTTOM TERMINAL ON THE TRAC PUMP. THIS IS INCORRECT. THIS IS BACKWARDS. DO NOT CONNECT THE WIRES THIS WAY. The positive voltage is applied to the TOP terminal in the connector.
Happy bleeding.
dave"
Again, keep in mind this was written for a Supra, NOT an SC400, but the basic principle ought to be the same.
Following is a procedure we use for the Supra (originally written by Dave Ruder back in 2000 or before).
I used this procedure for my Supra, (before I removed my TRAC system completely) and it worked a treat . The TRAC pump ejected probably 3-4 ounces of the filthiest brake fluid I'd ever seen, so I think it was well worth doing.
"Some people have emailed me wanting trac bleeding intructions. While it really isn't absolutely necessary to bleed the trac system, it is the only way to change the fluid that is trapped in the trac pump and the trac control valves. As brake fluid absorbs water, it accelerates the corrosion process on all the metal parts in the brake system, including the trac parts, so it's not a bad idea to change the fluid occasionally to prevent future problems. Also, if you EVER let the reservoir run dry, like if you pull the calipers and let the fluid drain out of the lines, you probably introduced air to the trac system and should bleed it if you want it to function exactly as it was designed.
The manual calls for a special tool to do the procedure. I've traced the wiring paths, and 'made' this special tool, which is nothing more than a couple wires with appropriate connectors on the ends.
One last thing. Others have mentioned that the trac pump can be operated simply by 'jumping' the relay in the passenger side of the engine compartment, but I'm convinced that this will lead to incomplete bleeding of the trac system. The instructions in the manual ask that the ignition switch be turned to ON while the trac pump is operating, and I've discovered why this is recommended. I've spoken personally to one of the engineers that DESIGNED the ABS system for the mkIII and mkIV thunderbirds, and he informed me that when the ign switch is turned to 'on', the system performs a self test where it energizes all the solenoid valves one at a time and runs a self diagnosis. If the trac pump is operating and the bleeder nipple is open when the 'self check' is performed, any air bubbles trapped against the ABS or TRAC valves will be allowed to escape. This is the only way to get rid of these air bubbles. If air bubbles are present in the trac or ABS system, it won't make the car 'undrivable', and it may not be obvious in how the ABS and TRAC systems operate, but without a doubt the systems will function better with zero air in the system.
So, if you want to bleed the trac system, or change ALL the fluid, here is how to do it on a 1994 MKIV Supra.
1) Make a 'jumper' wire by attaching appropriate ends on two 4 foot wires that will allow you to attach the wires to the + and - on the battery, and will also allow you to attach the other ends to the male prongs in the trac pump connector. The ends you'll need to attach to the jumper wire are female, and are in the shape of a slot. These can be purchased at an auto parts store, or radio shack The wires should slip onto the appropriate prongs inside the trac pump connector, and SHOULD NOT BE ALLOWED TO TOUCH EACH OTHER, or you will have a direct short and that will MELT your jumper wire and possibly cause a fire.
2) Identify the trac pump connector. It is directly in front of the brake master cylinder. Seperate the 1/2's of the connector by squeezing the retainer and pulling the 1/2 nearest the driver's fender toward the driver's fender. After you have pulled the driver's side 1/2 of the connector off, that side will hang free, while the side nearest the passenger will remain attached to a bracket. It is the side nearer the passenger that remains attached to a bracket that you will attach the jumper wires to. You will see three prongs inside the connector, and three wires exiting the back of the connector. The TOP wire is solid blue. The middle wire is yellow. The BOTTOM wire is black or dark green (I'm colorblind, sorry). The wire colors are DIFFERENT on the now free hanging connector nearer the driver's fender. The TOP wire is Blue with a yellow stripe, the middle wire is white with a green stripe and the BOTTOM wire is White with a black stripe.
3) Carefully attach one wire to the top prong in the connector that is attached to the bracket. This prong corresponds to the solid blue wire.
4) Carefully attach the other END of this same wire to the positive terminal of the battery.
5) Carefully attach one end of the OTHER wire to the bottom terminal of the connector attached to the bracket that corresponds to the solid BLACK wire. THE WIRES MUST NOT TOUCH EACH OTHER, AND THEY SHOULDN'T TOUCH THE MIDDLE TERMINAL. THEY SHOULD ONLY TOUCH THE APPROPRIATE POST IN THE CONNECTOR.
6) Briefly attach the other end of this last wire to a metal part of the chassis that is well grounded, like the nuts on the driver's shock tower. THE PUMP SHOULD OPERATE. Don't make this last connection to the negative terminal of the battery, as the spark created may cause an explosion. REMOVE the wire from the shock tower nut to stop the pump now, and hang it somewhere where it won't contact a ground point and operate the pump.
7) Locate the bleeder nipple for the Trac Actuator, located between the master cylinder and the driver's fender. Remove the little rubber cap on the nipple, and attach a hose to the nipple. Loosen the nipple so the fluid can escape, and be prepared to catch the fluid in a jar or cup and don't let it contact your paint.
8) The trac pump should NOT be operating right now.
9) Start the car's engine
10) Attach the last wire to the shock tower to start the pump operating.
11) LET THE PUMP OPERATE for 60 seconds before tightening the bleeder nipple. Don't open the nipple too far or the fluid will pump out too fast and you'll run out. There must be adequate fluid in the reservoir, and the reservoir can run dry in one of its three compartments while there is plenty of fluid in the other two. The reservoir is divided front to back into three compartments below the LOW Line, so WATCH CAREFULLY, and if it is draining too fast, close the bleeder nipple a little to slow the process. Fluid should be pumping through your attached hose and into the cup at the open end of the hose.
12) After you tighten the bleeder nipple all the way to stop the fluid from escaping, you must let the trac pump operate for an additional 30 seconds.
13) Remove your jumper wires and stop the pump.
14) Shut off the car. Clear the trouble codes by resetting the ECU. The procedure is supposed to trip a code.
The trac bleeding should be done AFTER all calipers are bled.
NOTE: If you look really closely on page BR-11 in the manual, you'll see a picture of a jumper wire connecting the battery and the trac pump connector. IT APPEARS IN THIS PICTURE THAT THE + TERMNIAL OF THE BATTERY IS CONNECTED TO THE BOTTOM TERMINAL ON THE TRAC PUMP. THIS IS INCORRECT. THIS IS BACKWARDS. DO NOT CONNECT THE WIRES THIS WAY. The positive voltage is applied to the TOP terminal in the connector.
Happy bleeding.
dave"
Again, keep in mind this was written for a Supra, NOT an SC400, but the basic principle ought to be the same.
If the connections are made as posted above, the TRAC pump will run backwards, i.e., it will try to empty the system into the reservoir. This is obviously incorrect.
The top connection (pin 1) of the three connections should be connected to NEGATIVE, and the bottom connection (pin 3) should be connected to POSITIVE.
The Toyota manual is actually correct. If anyone has any doubt just trace through the TRAC wiring diagram and look at the diagram of the connector.
Peewee
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What exactly is the TRAC system?
I thought it was Traction Control, which is a) purely electronic, and b) completely different/separate to ABS.
I thought it was Traction Control, which is a) purely electronic, and b) completely different/separate to ABS.
It is traction control, but there's different variations of TRAC.
The type mentioned in post 2 above is with regard to a 1994 Supra MkIV and that version of TRAC incorporates the rear brakes into the system, therefore there is the need to occasionally replace and bleed the TRAC system.
Peewee
New Member
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- 2,635
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- Perth, Western Australia
Ahhh, fair enough.
