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bigsexypirate
New User
Mar 19, 2008, 7:37 AM
Post #1 of 5
(3750 views)
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I have a 1998 Dodge Dakota (3.9L 2WD) with approx 160,000 miles on it. Recently the speedometer, odometer and cruise control quit working, simultaneously. I have already replaced the speed sensor in the back of the tranny hoping that would fix the problem, not dice. Also, the "brake" and "ABS" light stay on all the time....last problem is the occasional backfire and complete power loss (and stalling under braking at signals)....I am pretty good with cars but these problems seem to have got me confused...THANKS
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Mar 19, 2008, 8:21 AM
Post #2 of 5
(3742 views)
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Can you get a full code reading for this? Would help right now!
T
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bigsexypirate
New User
Mar 19, 2008, 8:27 AM
Post #3 of 5
(3741 views)
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Thats one of my problems, I used a Scan Tool and the only code I got was for the Vehicle Speed Sensor reading low voltage...I was hoping that there was a relay, or control module, or something that controlled all 3 of those things (speedometer, odometer and cruise control)
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Mar 19, 2008, 10:11 AM
Post #4 of 5
(3736 views)
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Have you scanned again after the speed sensor was replaced? Yes - this sure points to one common problem that might even be wiring or a connector or computer itself failed,
T
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DanD
Veteran
/ Moderator
Mar 20, 2008, 5:01 AM
Post #5 of 5
(3731 views)
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You are going to likely need a scan tool the can interpret Chrysler Collision Detection (CCD) bus signals; (where the name came from I don’t know?) so that you can observe the communications between the different modules.
Most generic scan tools do not have this ability; which means you will need a Chrysler’s Diagnostic Readout Box (DRB) scanner.
The vehicle speed sensor signal goes directly to the Powertrain Control Module (PCM). The PCM converts this signal, so that it can be sent in a form that is (for the lack of a better phrase) in computer language to the different modules that require these signals.
Their reasoning for doing this is that they can reduce the size of the wiring harness because they can send several different signals down the same wire. Each signal has its own code attached to it, which the different modules (computers) can recognize as their required signal and ignores the others.
What you need to do with the scan tool, is see if the speed sensor signal is getting to the PCM; is the PCM sending out the required signal to the instrument cluster and then see if the cluster can interpret that signal.
I know this doesn’t help you find out why your speedo is not working but maybe give you an understanding of what a tech is going to need and do to find the problem.
Dan.
Canadian "EH"
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