tdunk Posted February 10, 2009 Share Posted February 10, 2009 My accord has been a dependable family hauler since buying it new. 155k miles. Intermittent ABS light on has been diagnosed as failing control unit by dealer and control unit and accumulator by independent mechanic. Those problems are 1k-2k to fix to spec. I can live without ABS. Real problem though is occasional pressure loss at the pedal. I don't think this is related to ABS unless you all tell me otherwise. I have not been able to isolate to anything i can repeat. Most recently, it was several weeks between instances. Usually pedal will go soft after stopping, have had it feel softer while stopping. Dealer said it might be master cylinder and wanted me to pay $600 to see if that might fix it. No leaks, system is full. Could it be as simple as some air in the lines? TIA. Link to comment Share on other sites More sharing options...
James Matteu Posted February 10, 2009 Share Posted February 10, 2009 Yes, it could be as simple as some air in the lines. It could also be the Brake Master Cylinder, the soft lines, the ABS, etc. You have some investigating to do. This is not something you're going to figure out without inspecting the braking system, and I wouldn't start ruling components out before doing a thorough inspection. Link to comment Share on other sites More sharing options...
tdunk Posted February 10, 2009 Author Share Posted February 10, 2009 Yes, it could be as simple as some air in the lines. It could also be the Brake Master Cylinder, the soft lines, the ABS, etc. You have some investigating to do. This is not something you're going to figure out without inspecting the braking system, and I wouldn't start ruling components out before doing a thorough inspection. thanks James- The randomness is what is confusing me. I also forgot to add that the soft brake problem is not tied to the ABS light telling me there is an ABS problem. Would pulling the fuses for the ABS effectively lock out the system and limit the troubleshooting to the basic brake system? I am noob to this kind of troubleshooting but mechnically able with some good info and since two shops are shrugging their shoulders, any help would be appreciated. Link to comment Share on other sites More sharing options...
James Matteu Posted February 10, 2009 Share Posted February 10, 2009 How do you know the ABS light has nothing to do with your problem? What code is stored in your ABS Control Unit? You can remove the under-hood ABS Relay, but this will only prevent your ABS system from attempting to function; it will not isolate the ABS system from the brake system. If you follow the lines coming from your Brake Master Cylinder, you should see that the ABS system is part of your brake system and cannot be isolated electronically. You would have to physically remove the ABS lines and cap the ports on the Brake Master Cylinder. I can say with confidence, that you would be doing more work than had you actually diagnosed the problem outright. Link to comment Share on other sites More sharing options...
tdunk Posted February 10, 2009 Author Share Posted February 10, 2009 How do you know the ABS light has nothing to do with your problem? What code is stored in your ABS Control Unit? You can remove the under-hood ABS Relay, but this will only prevent your ABS system from attempting to function; it will not isolate the ABS system from the brake system. If you follow the lines coming from your Brake Master Cylinder, you should see that the ABS system is part of your brake system and cannot be isolated electronically. You would have to physically remove the ABS lines and cap the ports on the Brake Master Cylinder. I can say with confidence, that you would be doing more work than had you actually diagnosed the problem outright. Ok, I am not trying to assume anything. I was only trying to point out that the soft brakes/pressure loss has happened when the ABS light is not lit and also when it is lit. As I mentioned, I am noob at this level and am here because two different shops have not had definitive answers but have suggested extremely expensive repairs. At this point, I am trying to get some concrete info to decide if it makes sense to repair or cut my losses. I would like to figure out what is going on and would appreciate some help from the experienced folks here. My independent shop said the codes it was showing indicated the ABS control unit was bad and the accumulator was bad/going bad. I don't have the specific codes. I will invest the time/effort into troubleshooting this problem completely if you think there could be a cost effective solution. I appreciate any and all help. Link to comment Share on other sites More sharing options...
James Matteu Posted February 10, 2009 Share Posted February 10, 2009 First, get a jumper wire and pull the ABS codes. Okay so I pulled my codes... Code 4-1: Description: Wheel Sensor, Right-front Reason: Funny story, I was doing a brake job and left one of the bolts behind the hub loose. A few days later it finally worked itself loose and fell out. Just not before it could lodge itself between the wheel sensor and the CV Axle. The bolt ground the gear pulser smooth. Code 1-0: Description: ABS pump motor over-run Probable Causes: 1. Air mixed in the ABS brake fluid 2. Pressure switch stuck OFF 3. Open circuit between the pressure switch and ABS control unit 4. Open circuit in the P-SW circuit between the pressure switch and body ground, or a poor ground 5. Drop in pump discharge volume 6. Leaking outlet valve 7. Leaking relief valve 8. ABS brake flluid leakage 9. Faulty ABS control unit I am going to reperform the bleeding procedure next payday. Again, any ideas, feel free to contribute. I am thinking I have some kind of slow leak and/or air in the pump. I will re-bleed and pressure wash the engine bay. This way I will be able to spot any new leaks, versus any slow weeping seals. FYI, Honda T/N 07PAZ-0010100 ($5.00 at Honda) will pull codes from the ECU for the PGM-Fi as well. Second, perform the Brake Booster Function Test: 1. With the engine stopped, depress the brake pedal several times to deplete the vacuum reservoir, then depress the pedal hard and hold it for 15 seconds. If the pedal sinks, either the master cylinder is bypassing internally, or the brake system (master cylinder, lines, ABS modulator*, proportioning valve, or caliper) is leaking. 2. Start the engine with the pedal depressed. If the pedal sinks slightly, the vacuum booster is operating normally. If the pedal height does not vary, the booster or check valve is faulty. 3. With the engine running, depress the brake pedal lightly. Apply just enough pressure to hold back automatic transmission creep. If the brake pedal sinks more than 25mm (1.0 inch) in three minutes, the master cylinder is faulty. A slight change in pedal height when the A/C Compressor cycles on and off is normal; the A/C Compressor load changes the vacuum available to the booster. Third, perform the Brake Booster Leak Test: 1. Depress the brake pedal with the engine running, then stop the engine. If the pedal height does not vary while depressed for 30 seconds, the vacuum booster is OK. If the pedal rises, the booster is faulty. 2. With the engine stopped, depress the brake pedal several times using normal pressure. When the pedal is first depressed, it should be low. On consecutive applications, the pedal height should gradually rise. If the pedal position does not vary, check the booster check valve. Lastly, perform the Brake Booster Check Valve Test: 1. Disconnect the Brake Booster Vacuum Hose at the booster or at the booster side of the Check Valve. 2. Start the engine and let it idle. There should be vacuum. If no vacuum is available, the Check Valve is not working properly. Replace the Check Valve and retest. * See, a problem with the ABS can manifest as an issue with the rest of the braking system. Link to comment Share on other sites More sharing options...
big.mikey Posted February 16, 2010 Share Posted February 16, 2010 i have a 95 accord it now has 300800 miles. yes that is right alot of miles. I got the car with only 65000. my abs light was on forever....till it burned out. brakes work good just no abs. My brakes got soft a couple years ago. It turned out that the lines got rusty (cleveland, ohio) going to the back brakes. They had to replace the lines from the front to the back they had to go around the gas tank it was about 600 i think. Link to comment Share on other sites More sharing options...
James Matteu Posted February 16, 2010 Share Posted February 16, 2010 Dead thread dude, that guy flaked out when I told him what the deal was. Link to comment Share on other sites More sharing options...
big.mikey Posted February 16, 2010 Share Posted February 16, 2010 tried to help?! Link to comment Share on other sites More sharing options...
big.mikey Posted February 16, 2010 Share Posted February 16, 2010 wow i just saw this was last year Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.