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tech 1 bleeding procedure

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The Tech 1 can do complete diagnostics as well as pull trouble codes specific to the abs system. I have the GM manual, as well as the brakes service notes....I can scan a few pages if you can tell me what you specifically need an answer for.

The Tech 1 bleeding procedure cycles the solenoids that can help expell any trapped air. I have been told that the pedal "adjusting" under foot pressure is usually a sign of this.

Do you have a specific issue with your brakes?

Edited by Paul93Lotus
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No specific issue quite yet, I just bled my brakes manually last night after replacing the front calipers/rotors/pads and pads only in back. My pedal is a bit soft today so I will try bleeding again. Maybe I will try using the tech 1.

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OK I will try the manual procedure again. My ABS light came on solid was fine for around 40 miles since bleed and then it came on, I think there is some air in the system. Yes I was able to borrow a tech 1 with abs cartridge.

The codes indicate brake sw/accumulator or hydraulic leak, but the accumulator is new and there is no leak. It might be my brake switch as well so I will check that.

Edited by nodemgr
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Exactly what code numbers did you get?

This info taken from a GM factory manual for the Delco PM III system...which is more detailed than the Lotus manual:

1. A solid light indicates that the Antilock Brake controller has detected a fault and disabled part(front wheel portion) or all(front and rear wheel portions) of the antilock system. It will not disable the conventional power brake system.

* There are several notes regarding prolonged vehicle operation may futher damage the ABS system.

If you have the codes it will help diagnosis. Hopefully it is just the brake switch at the pedal. If your brakes light stay on even when the pedal is not down that can cause a solid abs light. Have someone stand behind your car and observe the brake lights when you hit the brake pedal. Also just on chance you have not switched any brake bulbs to LED? That can cause problems with the abs believe or not....has something to do with the resistance in the circuit. An regular bulb has A LOT more resistance than an LED.

Consider yourself lucky that you have access to the TEch 1 Lotus cartridges...they are extremely rare, and since Vetronix was bought from Bosch, I believe no longer made.

Oh, and the hydraulic leak part could be internal seal problems within the solenoid assemblies or within the master cylinder.

Worst case scenario the system can be rebuilt by Prior Remanufacturing. Also know that the rear of this system is not identical with the GM parts...Lotus must have changed some parts where the pedal rod comes in contact with the master cylinder assembly. Don't ask me how I found out. :blush:

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Great thanks for the info. I haven't switched to LED, but I have replaced the 3rd brake light bulbs with newer ones.

The codes were A062 and A056, but I didn't clear them from previous drive cycles so I'm not sure they both were set this time.

I rebled tonight and I started by bleeding the master cylinder body. A decent amount of air seemed to come out of the right side pipe nut so I am hoping that was the issue. There were also a couple of large bubbles that came out of the left front caliper bleed screw.

Would I be able to tell if there were internal hydraulic leaks? When I press down the brake pedal I get a squishy sound coming from the master cylinder area...almost like there is an internal leak...but maybe that sound is normal.

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From the Service Notes: (HOPE THIS CAN HELP) Sounds like the pump time is running too fast, since code 56 refers back to 62 (they can come up in tandem)



The Accumulator is precharged to approximately 1200 PSI with nitrogen gas. The Pump Motor

maintains system pressure between 2200 PSI and approximately 2700 PSI. The Accumulator Switch Motor

Control closes when the pressure drops below 2200 PSI. This grounds the Pump Motor Relay Coil causing

voltage to be applied to the Pump Motor and Pump On Input. Whenever the Pump Motor is on, the Pump

On Input will have voltage applied to it. The Pump Motor will run until system pressure is restored to

approximately 2700 PSI.

CODE A062 will set when the ABS Controller detects short pump run times of less than 1.4 seconds in


Test Description: The following provides

an explanation of the procedures being followed in

the facing trouble tree.

1. If the pump run time from

Edited by Paul93Lotus
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Well in the 4 days I've been driving the car after bleeding the master cylinder and clearing the codes the ABS light has only come on once, and it went off on it's own before the next drive cycle. I got a code 62 only. The accumulator is brand new. I've since found out my alternator is about to give up the ghost(it's showing around 11.9V to the ECU when idling) so I think this could be part of the problem. I am going to replace the alternator and see if I have any other issues and then troubleshoot from there. Thanks for the help all!

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