ABS problems on the van

I am having ABS issues on my van. The ABS brake system kicks in at very low speeds on dry pavement. There is a service bulletin about rust on the mount point of the sensor causing it to pull away from the hub so the signal is erratic. That would be a simple fix as the sensor is $200. I can not find a cheap overseas replacement part even on Ebay. My scan tools shows a couple of generic ABS chassis codes:

C0281 (chassis code - ABS) Brake Switch Circuit
C0223 (chassis code - ABS) Rt Front Speed Signal Erratic

I suspected the right front wheel so this confirms it. The test procedures specify resistance and voltage readings for the sensor. Getting the voltage reading is going to be a trick as I can not spin the front wheel as I have all wheel drive. I will have to disable the ABS then rig up a cable to attach to the harness so I can roll the van down the driveway to measure the AC pulse train. The voltage is very low (approx 100 millivolts) so noise is going to be a problem even using the oscilloscope. The service bulletin indicates the signal should be at least 350 mV but this document says greater than 100 mV. So much for consistent documentation.

The procedure also measures the cable from the sensor to the electronic brake control module (ECBM). It states that faulty wire connections is a leading cause. The darn EBCM is attached to the frame under the van. That is the dirtiest place you could put the thing.

I am a little confused by the C0281 code for the brake switch circuit. The description indicates that this code may set if the there is an ABS fault of at least 500 milliseconds. That would have set by the C0223 code but then in the next line it says the code only sets if there is an open or short in the brake switch circuit wiring. For now I will assume it is setting because of the sensor signal. Fix that and then see if C0281 comes back.

The last item in the correction chart is to replace the ECBM. Unfortunately you have to have a scan tool that communicates to the device. Consumer scan tools only read diagnostic codes. You need on of the expensive units to talk to the devices. You have to set the tire diameter for the vehicle in the ECBM. Crap! If that is bad it is back to the dealer to replace that darn thing. I bet they get a lot of $$$ for that module.

Over the weekend I hope to get a chance to investigate the sensor/wiring.

UPS Batteries

Test complted on the batteries in the UPS.  There are four PowerSonic PS-1272 7.2Ah batteries in the UPS.  Three of the pass as shown in this graph:

 

 

One battery would not carry any load.  That one is the problem. 

 

Results of the test in text format:

 

 

 

UPS Failure!

I have a 1400 watt rack mounted UPS that powers my computers. The computers and UPS are in a rack. Yesterday I discovered all my computers rebooted in the early morning. The UPS appeared to be running fine by way of the indicator lights on the front. I gave it the big test by pulling the power cord from the wall. The entire rack went dark. The UPS was running in bypass apparently. I brought the UPS back on line and now I had a red malfunction light on the front panel. This is a refurbished UPS which is one of two that I have. They are about a year old. I swapped the failed unit for the other one which is only running one PC downstairs. I am now in process of checking the batteries. I have noticed the battery charge status leds have been flashing. I have a technical bulletin about that indication. The document talks about a calibration process that may remove that warning. Before I do that I need to test the batteries to make sure they are still in spec. There are four batteries in the UPS. They are 12 volt Power Sonic 7.2AH batteries. They are connected in series and parallel providing 24 volts at 14 Ah. I have about 650 watts on this UPS so that only gives me about 10 to 15 minutes run time before they crap out.


I test the batteries using a computerized test fixture. This is a device by West Mountain Radio. Plugs into the USB port on the PC and by running the provided software you can do a load test and see if the battery meets specification. You can see the resulting chart after the test on the first battery. You set the load current as indicated by the specification. Most batteries of this type are tested over a 10 or 20 hour rate. Power Sonic lists the spec for both 10 and 20 hours so I used the 10 hour rate. For a 7.2 AH battery that is 0.700 Amps. They also specify the "dead" voltage which is typically 10.5 volts for a 12 volt battery at this load current. As you can see from the chart I got 8 Ah out of the battery by the time it hit 10.5 volts. So battery 1  is good. This battery goes on the charger and I connect up the second. At ten hours a test this will take a little time.


Chart after test of first battery



Batteries ready for testing. Battery #1 connected to the test fixture



Batteries as wired up in the UPS unit

New Toy

I picked up an HP 5372A Frequency and Time Interval Analyzer. This box take time interval measurements: time interval, continuous time interval, and +/- time interval. A time interval is a measurement of elapsed time between two electrical pulses. I will use it for testing and comparing oscillators. As I sit here playing with this unit I wonder what kind of unusual time interval analysis has been done using this type of device in industry or the military.


I have completed the functional tests out of the manual. The unit appears to be in good shape and calibration.


 

The SUN's solar activity and climate change

All this crap about man being the cause of global warming never ceases. In the political arena man is to blame and everyone totally discounts the effects of the SUN. What a bunch of moron’s using nature’s normal cycle as an excuse to generate taxes (cap and trade/carbon emission reduction) and force lifestyle changes on the population. Years ago I took a course on the Sun’s effects on radio propagation. This was long before Owl Gore and his CO2 vs temperature chart (which he read backwards by the way). It was quite apparent that the 11 year solar sunspot cycle’s overall trend has the greatest influence on the Earth’s temperature. Much more than what man can do to the planet. We have been at the bottom of the last solar cycle for a much greater period of time then cycles in the past. If the new solar cycle had followed the pattern of previous cycles we would now be a couple of years into a rising sunspot count. This pattern has not occurred in this cycle. We have been in a period of no sunspot activity. We have been in the low period of sunspots for a few years. The comment below speaks of the period of time where NO sunspots have appeared at all. Continued low solar activity will drive the Earth temperatures down. In the current political arena the wording is changing from “global warming” to “climate change”. That way they cover all bases no matter what the temperature does. They can continue to spread lies about climate change to effect new taxes and control of the population.


This is comment was in a DX news letter that follows along with what I found when I took the propagation course.


Out in space the sun remains on a record pace at 51 days without sunspots, and no expectations of any change soon.  We’ll be in the top 3 longest quiet periods by Wednesday evening (tied with 54 days from 1879) and by late next week we’ll head into the 2nd position as we surpass 63 days from 1901. The daily solar observations began in 1849, but we know from other observations between 1400 and 1830 that these
periods of sunspot minimums were associated with a 400-year stretch known as the Little Ice Age. The only problem with observations from that time is that there were no telescopes and satellites with the observational power we have today. In other words, the long periods without sunspots are even more impressive now because we can pick out the smallest sunspot, ones that would have been missed 100 to 200 years ago. We
won’t know if this is true for a long time, but at this point there is no reason to discount the idea that we’re heading into another Little Ice Age, or possible a major ice age. Time will tell…