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Loss of power....jumping speedo....

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  #11  
Old 03-20-2009, 07:18 PM
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I have cut and torn my drivers side ABS wires near the a-arm 3 times. All I ever got was an ABS light, with no other problems. There is no polarity to the ABS sensors, just fix the wires and save your money. I do not see how this could be related to your earlier problem. That sounds more computer / ground cable related.
 
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Old 03-20-2009, 08:06 PM
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Here is one reply I got from a forum member....

Well I'll tell you it's looking like it's a front ABS speed sensor problem. Going to replace them both on Fri. I found out I have a 1st design ABS system, that is where the sensors are "fixed" to the dust sheild. The ABS sensors work together with the transmission, transmission speed sensor, and the computer. They all have to be WORKING, together, or it throws everything off, just like in my case. You could have the same problem. My ABS light goes on, then that's when everything starts to "flip out". I'm just going to replace both sensors and hope for the best.

And here is another.....

But.........I do want to run something by you guys that I was thinking about which MAY have something to do with this acting up. About a week before I had this problem, I had disconnected the ABS in both front wheels. {I hate ABS in winter} first time I have done this. The car ran fine with it disconnected, for about a week, then that's when these problems started. I decided to reconnect the ABS system, thinking that I was going to have to take it in to get it looked at, so I didn't want the ABS light on. Well that day, I reconnected it, the car,while on the freeway, later that day, seem to go back to normal operation. Did this have something to do with screwing upthe PCM?????Thanks.

And the last one....
Yes the ABS is one of the sensors the puter uses to adjust engine/tranny performance. It compares tire speed (ABS) to driveshaft speed (VSS).
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Old 03-20-2009, 08:48 PM
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Originally Posted by bandidolenny
I have cut and torn my drivers side ABS wires near the a-arm 3 times. All I ever got was an ABS light, with no other problems. There is no polarity to the ABS sensors, just fix the wires and save your money. I do not see how this could be related to your earlier problem. That sounds more computer / ground cable related.
Yep, all you have to do is fix the wires if that is the ABS issue. You want to test the speed sensor output with a multimeter set to the mV-AC scale. When you spin the wheel (speed does not matter), the output should read between 200mV-AC and 350mV-AC. If it is under 200mV, the ABS computer will trigger a code for a bad sensor.

Oh and there is no need to PM me as well as post. I will respond, just like everyone else, when I see your thread and have the time.
 
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Old 03-20-2009, 09:29 PM
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Thank you ALL for your help...just picked up a Timken hub ***'y....I'll keep you all posted....hope this helps others as well.....
 
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Old 03-20-2009, 10:31 PM
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Does it seem odd that this happened for the first time back in October and then nothing at all until 5 months later. Shouldn't it have happened more? Can it be that intermittent?
 
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Old 03-21-2009, 07:22 AM
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A front hub will not cause your speedometer to jump around and definitely has nothing to do with the tach. Unrelated items completely. The VSS (at the back of the transfer case) is what the PCM uses for the information which it relays to the cluster. The tach is controlled by the PCM as well and the CKP (crankshaft position sensor) is what the PCM uses to determine engine RPM.

This problem seems to center around the communication between the PCM and the cluster. This could either be a connection problem at the back of the cluster (either wiring or a cold solder joint), a bad cluster all together, or it could still be an ignition switch failure.
 
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Old 03-21-2009, 11:50 AM
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So is it worth it to replace the front hub ***'y? Where exactly is the VSS? How do I check it? What should my next move be? What does the ignition switch have to do with the tranny acting funny and not wantig to shift from a dead stop?
 
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Old 03-22-2009, 06:20 PM
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Well I replaced the hub ***'y today and now evertything seems fine...shifts better than ever....also pulled the plug at the transfer case and cleaned it well with contact cleaner......Out of ideas....just gonna drive it until the next thing comes up.......
 
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Old 03-22-2009, 07:40 PM
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I don't know how you go about finding this out from chevy, but in my 05 Chevrolet new there was a problem with the instrument cluster and if it failed before a certain mileage/timeframe, more than warranty period, they would replace it for nothing. Well of course mine went out after 110,000 miles so we got to pay for a new one.
 
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Old 03-22-2009, 08:16 PM
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VSS is in the tail housing on the back of the transfer case. As far as testing it goes, I do this with my scan tool, but that is not something that most diy'ers can do.

I probably should have put it more blatant in my last reply.. Pull the cluster! Look at the connection at the back. If you see cold solder joints (cracked out solders that look dull), repair them. If not, you may want to look at getting another cluster from the junkyard to swap in.

As far as the ignition switch goes, it controls power to the entire vehicle via two main voltage supply lines (IGN1 and IGN2). If one of these lines drops out while driving, it can cause a whole host of problems.
 
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