brantgab

Thanks for the comments. I flushed the brake lines a couple of weeks ago - there is no air in the system. Didn't think to leave the ignition on and check pressure at which the pump comes back on. I'll rerun the tests when I replace the accumulator, and if anything seems out of line I'll hook the gauge back up. Thanks again.

I received my pressure gauge today and ran some more tests. Here are my observations: I first ran 12v directly to the pump and the pressure reached 3000 psi in 4-5 seconds. 1 press on the pedal and the pressure dropped all the way to 300 psi. 2 presses and the system was totally depressurized. I turned the ignition to the on position and the pump kicked off at about 2750 psi. It took about 4-5 seconds to reach that pressure. From there the pressure slowly dissipated: 2500 psi in 15 seconds 2300 psi in 1 minute 2000 psi in 3 minutes The pressure continued to slowly dissipate until it dropped to about 1850 psi where it held. Again, 1 press on the pedal dropped it to 300 psi and 2 presses totally depressurized it. I measured the difference in fluid level between pressurized and depressurized and there is only about 1/16" difference. It seems to me that the pump is working fine, although it seems to get up to pressure very rapidly. The pressure switch seems to work as well, shutting the pump off where it is supposed to. I couldn't test at what psi the pressure switch kicks the pump on because the system depressurizes so rapidly. My earlier tests showed the pump engaging with every press of the pedal, so I'm thinking that the switch is fine. I'm thinking that the problem is with the accumulator; It seems as though there is no nitrogen in the bladder, which is why there is little difference in fluid levels. That would also seem to explain why the system pressurizes so quickly.

I was able to locate a pressure gauge and adapter on ebay, part #'s J 35604 & J 35604-88. There are others available there. Should have them in a few days and I'll see what kind of readings I get.

Well, I was able to run the pump for a minute to charge the system, but the test results were all the same. Now I am really at a loss.

padgett, I do have power brakes, but if I get on them too hard the pedal gets real stiff and braking is difficult.

I got back today and measured the resistance of the main valve at 4.5 ohms. I retook the test and got similar results: 1) both lights on with 1 pump 2) brakes are hard on 1st pump 3) red light stays off, never comes on to begin with; yellow light off in 2 seconds. 4) pump off in 2 seconds 5) the pump runs every time I press down the pedal. *** 6) no difference in fluid level 7) feel tap and hear thump *** When I first took the test I didn't think the pump came on at all in test 5. I mentioned that I would hear a sound different to the sound of the pump. What is actually happening is that the pump stops running so quickly that the sound of it is being drowned out by the sound of the fuel pump running. The sound I am hearing every time I press the pedal in test 5 is in fact the pump.

I did not allow the reservoir to run dry at any time while flushing and have performed no other brake work. I just bought the car recently and this problem existed when I bought it.

I think I may be mistaken on test 5. When performing the test I never heard the pump come on the way it does when turning the ignition on; However, I did hear a different noise every time I pressed the pedal. Thinking back, when I flushed the brakes I was able to keep the pedal pressed down and the fluid kept pumping out the bleeder for as long as I kept the pedal down. I think the correct answer to test 5 might be every time. I am away from home for a few days and can't do any further testing until I get back.

I actually flushed the brake system last week. What parts of the test do you find conflicting and why?

I checked the pressure switch connector and there is no moisture present

Under normal braking conditions everything works fine. The yellow ABS light comes on initially but goes out as I continue braking. If I get on the brakes hard, the pedal becomes really stiff and I have to stand on it to slow down. test results: test 1 - yellow 1, red 4 test 2 - 1 pump test 3 - red never came on, yellow off in 2 sec test 4 - pump off in 2 sec test 5 - I stopped at 100 pumps - never came back on test 6 - no change test 7 - feel tap and hear thump

I'm getting codes 21 (main valve) & 12 (EBCM) from the ALDL. I'm quite certain that the accumulator is shot. Would this be what is causing the 21 code? Is there any way to test the EBCM to make sure it is working properly?

My new BCM arrived today and I installed it. Easy change out. Everything is working great now. Thanks everybody for all your help

I'm waiting for my BCM to arrive. I've never changed out a computer before. Any tips or precautions?

I repeated the test with the connector connected. I'm getting a constant 5 volts; when the ignition is off, and when the ignition is on, regardless of fan speed.

I checked my ground connections today. They were all tight and had little if any corrosion on them. I cleaned the connections and re-tightened them. I performed the test on the blower module connector again and was getting a constant 9.6 volts at all speeds - off, low, auto & high - with the ignition on. I tested the voltage on the purple and white wire of the HVAC programmer connector and was getting 5.0 volts with the ignition off. I turned the ignition on and the voltage did not change. I was unable to test at different fan speeds because I was unable to access the climate page of the CRT. Typically, when I power up the ignition the CRT wakes up on the summary page. With the HVAC programmer disconnected the CRT was waking up on the radio page and I was unable to access anything else.

The only other trouble I a having is that the instrument panel lights do not come on. I am unable to adjust the brightness of the dash/display lighting. I intend to change the twilight sensor to try and fix that. Everything else seems to be working fine.

The fan was not running during the test. Yes, I was refering to checking auto mode. The programmer I installed was rebuilt. I'll go through the ground connections and see if that corrects anything.

I did the test, and when I turned the key to the run position and had the fan off my meter was reading 7.2 volts. Changing the fan speed to high kicked it up to about 9.2. Eventually it settled to around 8 volts and remained there through the other changes.

Ronnie, This is the blower control module I installed is ACDELCO Part # 1572530

Ronnie, There are no trouble codes. The fan does not run when the ignition is off. The fan always runs when the ignition is on. The fan speed is always on high, even when I select off, low, or auto. When I select off, the fan icon stops spinning even though the fan continues to blow on high. I'll have to check on the brand and part #. I picked up a volt meter today. All help is greatly appreciated. Thanks.

I tried disconnecting the both battery terminals for a few minutes but that did not fix anything. I did also check the diagnostics while the fan was set to off and got a reading of 0 volts. When I have the fan in the off position I cannot change the temperature. The CRT acts as if the fan is off even though it is still blowing. Is it possible that the new blower motor control module I installed is faulty?

I'll try that Ronnie, of course I had the battery disconnected during the install.

No, I received the climate control module (HVAC programmer) today. I installed a blower control module previously when the blower was running while the ignition was off. Now the fan will not shut off or change speeds while the ignition is on.

I got the new climate control module today and installed it. I still have the same problem: the temperature controls work, I can change the air flow (heat, defrost, bi-level), I just can't change the fan speed or turn it off. Suggestions?