2002 Dodge Caravan driveabilty

Tiny
JOE709370
  • MEMBER
  • 2002 DODGE CARAVAN
  • 3.3L
  • 6 CYL
  • 2WD
  • AUTOMATIC
Got a 2002 dodge grand caravan. Came in for overheating. Replaced bad water pump. When I backed the van out. Noticed the speedometer arm jumping. Hooked up my snap on scanner it will comuncate with the ecm. But not with trans, body controll module, air bags, cluster. It says is key on like i'm not getting power but just to the ecm. Don't know what to try next. Al fuses are good
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Monday, September 8th, 2014 AT 2:08 PM

7 Replies

Tiny
CARADIODOC
  • EXPERT
You have to use a different personality key than the one for the Engine Computer. As I recall, they're numbers 14 and 19, but there's a good chance I'm wrong. It will tell you which one to use on the screen.
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Monday, September 8th, 2014 AT 7:07 PM
Tiny
JOE709370
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Not sure what your talking about I have the modis ultra snap on scanner. It does'nt give me that chioce
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Tuesday, September 9th, 2014 AT 12:36 PM
Tiny
CARADIODOC
  • EXPERT
Sorry for the delay. I was out of town for a few days.

There's a small circuit board that plugs into the plug that connects to the vehicle. They call them "keys". Some of us call them "personality keys". Regardless, the Engine Computer requires a different key than the Transmission Computer. You have the key installed for the Engine Computer. That's why you could communicate with it, but you'll get your error message for any other computer unless you switch keys. It tells you on the scanner's screen which key to use for the computer you're trying to access.
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Wednesday, September 10th, 2014 AT 3:14 PM
Tiny
JOE709370
  • MEMBER
I have the new Lotus scanner from Snapon and it doesnt have keys. Thats why I misunderstood what you were saying about changing personalities. Scanner says is key on? All modules except ECM MODULE.. It will not connect with any other module. My question is does the ECM power and control all the other modules?
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Wednesday, September 10th, 2014 AT 7:04 PM
Tiny
CARADIODOC
  • EXPERT
I'm not familiar with that model. I went to the Snapon school for the Modis, Solus, and Ethos. You have something newer that apparently doesn't use those keys.

I was under the assumption that the power and data wires were all standardized on all vehicles with the OBD2 system, but there were also some manufacturer-specific terminals that will be different. Manufacturers' scanners are designed to work with just their vehicles, although the Chrysler DRB3 would work on any brand but just for emissions-related stuff. I suspect a different terminal is needed in the OBD2 connector for non-engine-related stuff, and that's why Snapon needed different keys for each vehicle to connect to those other terminals. Too bad they didn't standardize everything right away. Your scanner must select the right terminal either automatically, based on the vehicle you enter, or you have to tell it which wire to use, but you're saying there's no place to make that selection.

The best thing I can suggest is to contact Snapon directly. Do an internet search for "Horizon Center, Snapon" and see if there's someone you can contact in technical support. That Center is part of Gateway Technical College in Kenosha, WI. If they don't have an answer for you, there isn't one.
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Wednesday, September 10th, 2014 AT 7:28 PM
Tiny
JOE709370
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There's nothing wrong with my scanner its brand new its the modis ultra l can hook up to the ecm but cant comunicate with any other module does the ecm controll the power to all the other modules
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Thursday, September 11th, 2014 AT 5:38 AM
Tiny
CARADIODOC
  • EXPERT
I meant contact Snapon to ask them how to access the other computers, not because there's something wrong with your scanner.

The data buss originates in the Body Computer. Two wires connect between all the computers and the data link connector. That's the data buss. The Body Computer puts six volts on both wires, then all the computers take turns sending data on them and they read all the data from the other computers, then decide what to use and what to ignore. Where the difference comes in is at that data link connector you have the scanner connected to. The two data buss wires go there but there are other terminals for specific computers. It's my understanding those wires are for aftermarket scanners and they're not used with Chrysler's DRB3 scanner. That's also why the cheapy code readers can only read Engine Computer codes and no codes from any of the other computers. The Engine Computer is accessed on the data buss in the DLC connector.

I know from using my friend's older "intuitive" Modis that it's anything BUT intuitive, and it still uses keys. Yours is the first Snapon scanner I've come across that doesn't need keys, but then it has to either access all the other computers on the data buss or on those individual terminals in the DLC. If I couldn't access anything other than the Engine Computer, I'd be on the phone in an instant. You shouldn't have to fight with the tool or study a book, or heaven help us, try to figure out what a pile of icons mean. The tool is supposed to save you time and make your job easier.
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Thursday, September 11th, 2014 AT 9:12 PM

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