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Random ABS light and weird braking performance


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Let me say yesterday I got a good scare. Travelled up to McCall, ID to do my usual shopping. I normally take the back road around McCall to the store. When I started to approach the light I was easing into the brakes and all of a sudden the ABS is back pumping me not allowing to even stop. I was saying my prayers before I rear ended the car ahead of me. Then at the last 5 MPH of coasting the ABS tripped the light and brakes hit NOW. Missed the car ahead of me by inches. Now let me say I've replace all 3 speed sensors and been seeing the random light now and then. I've even tried with no shims in the front and now back to 1 and 1 in the front and the lights stay out for the most part. Now if you just lay on the brake hard like a panic stop now I get a wild jerk to the right. Quite spooky driving. Some times you can stab the brake and get the rear axle to lock one side or the other and not trip the ABS light. Really strange behavior...

So I better go check my AC noise. Guess what the alternator is at .07 AC volts. The alternator is done. So my weird random issues was a alternator problem. Now lets hope It's not fried the ABS computer. I guess Friday I'll be getting another alternator.

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The alternators these days are awful.  I fully expect in the next 10 years or so, that most of these trucks will be ABS delete due to the computers and controllers failing without replacement parts from Mopar. 

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2 hours ago, CSM said:

The alternators these days are awful.  I fully expect in the next 10 years or so, that most of these trucks will be ABS delete due to the computers and controllers failing without replacement parts from Mopar. 

Won't happen. Remember the ABS is the starting line for the speedometer signal so if there is no ABS computer then there is no speedometer.

 

5 minutes ago, Frankstein said:

Does exactly the same thing for a long time, like you Mike!   Sometimes no ABS light and other the light appears - disappears..    Change the rear sensor. nothing change.    

I highly suggest you test the alternator for excessive noise issues.

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Ok. This morning I decided to do more testing again. Unplugged the alternator and did some more test driving again. I will say the ABS is not tripping the lights but still behaving rather odd. I think the ABS unit has taken damage from the alternator.

While the alternator was unplugged (field lead). I did notice one thing that was strange is once the voltage of the system fell to 12.00 VDC the volt gauge drops all the way to 8 Volts and trips the check gauge light. That's rather crappy designed gauge to do that.

So while it was running I was measuring the AC output at the BATT post and the voltage was nearly ZERO bumping 0.01 barely. Plug in the field lead and the AC jumps hard spike of course of the initial hook up. But starts high at 0.07 and works it way back down to 0.05 with on loads. Alternator is junk in my eyes.

Now the question remains if the ABS computer is damaged... Time to hunt for ABS test tool I can barrow or get some to verify this unit.

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As for replacing the alternator I stopped in NAPA and had mine tested. According to the test machine it PASSED with .7 AC volts. The new alternator PASSED with 1.3 AC Volts. So no sale occurred. I figured I'll take mine home and rebuild myself. Now that I tore it down and found the issue is the alternator case is damaged and the rear bearing is flopping around in the case. So basically the whole armature is dancing in a orbit. The brushes are shot one brush is nearly wore to the point of no contact.

So now on the hunt for a good alternator.

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1 minute ago, Mopar1973Man said:

As for replacing the alternator I stopped in NAPA and had mine tested. According to the test machine it PASSED with .7 AC volts. The new alternator PASSED with 1.3 AC Volts. So no sale occurred. I figured I'll take mine home and rebuild myself. Now that I tore it down and found the issue is the alternator case is damaged and the rear bearing is flopping around in the case. So basically the whole armature is dancing in a orbit. The brushes are shot one brush is nearly wore to the point of no contact.

So now on the hunt for a good alternator.

I have my old one.  It still spins fine but was throwing over 1V ac.  I even have a box to ship it in.

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Rebuilding the alternator is extremely easy. It just the diode pack is expensive from LarryB.

http://www.fostertruck.com/catalogsearch/result/?q=alternator

He supplies the bearings, pulley, diodes and the brush pack. You'll need at least a two jaw bearing puller. As for replacing diodes and brushes that simple as pie. Can be done in minutes. Just need a few sockets and a phillips screwdriver to get that far. I was planning on going that way but when I found the bearing holder in the rear half of the case was wallowed out and the bearing was fine but the shaft moved about 1/16 of a inch I knew at that point I had to replace mine again.

More than likely the shaft movement and the wore brushes in mine where the cause of the AC noise issues.

As for the ABS module I called Module Masters in Moscow, ID and they can rebuild my ABS module in 2 days for $130 total cost. On top they give a 5 YEAR warranty. I'm going to talk to a shop tech tomorrow when I hand deliver my ABS unit. I want to find out if we can get ECM's and PCM's done.

Also I can tell you that if you unplug and remove the ABS module you can still drive the truck with normal brakes. There is no speedometer function at all. So you'll need a GPS to tell road speed. As for cruise control that is dead too because no speed signal. Also the BRAKE light is out and the ABS remains lit up. Which is odd.

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Wonderful news.

IMG_20151201_131745.thumb.jpg.3971910894

(MoparMom and Module Master Staff)

I had a nice little chat with the crew at Module Master in Moscow, ID. I did find out that Module Master does quite a bit. ABS modules, ECM of our Cummins, some of the Mopar modules are seal with the gelled sealant. Instrument clusters etc. So it worth the effort to give them a call and find out if they can fix your module. As for my ABS unit it will be repaired in 2 days for $130 buck and have the 5 year warranty.

I will be using them as a module repair source from here on out. Very professional crew!

Edited by Mopar1973Man
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All I can say is that I am very impressed with the Module Masters staff, work area and the "down home country how can we help you" attitude.  These are dedicated, warm, sincere people and I look forward to a future relationship with them.  This is a Plus for us....love Rosalie

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