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Greg
Dodge Dakota
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8/28/2007
17:19:58
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 Subject: Speedometer Need Help
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Message:
I just got BFG 33x12.5x15 tires and I have an automatic 97 dakota the speedometer is off and the shift points are screwed up to I would imagine what do I do to fix it?
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Kota Kid
Dodge Dakota
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8/29/2007
20:28:13
|  RE: Speedometer Need Help
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Message:
To fix the speedometer you will have to have the PCM reflashed either by a dealer or with a tuner, Superchips or Hypertech. Either option will let you program a different tire size into the computer, the tuner just helps make a little more power. That should also compensate for some of the shift point issue but it won't feel the same again unless you install gears to compensate for the increased tire size.
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Marv
Dodge Dakota
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8/31/2007
10:21:39
| RE: Speedometer Need Help
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Your Dakota has a Transmission Control Module (TCM), in addition to the Powertrain Control Module (PCM).
Talk to your local Dodge service dept about your situation. Find out what changes they make to the TCM and PCM so the transmission will shift properly, and the vehicle speed and mileage displays will be correct. If you plan to change the differential gear ratio, make sure that change is part of the information they put in the control modules, so when you do re-gear, it'll already be set up.
It's not a "reflash," it's simply a matter of changing a few settings in those modules.
As for the 33" tires - to compensate for those, you're should re-gear the differential(s). 4.10:1 should do nicely, assuming your stock tires were 31".
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Kowalski
GenIII
8/31/2007
15:50:11
| RE: Speedometer Need Help
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Message:
Marv - Changing the settings is a reflash, or custom flash. Why do you think that isn't a reflash ?
As these guys both recomend, it might take a gear change to get things shifting right again. Otherwise, you're going to feel like it's down on power, even altering the shift points - you've effectively gone to higher gearing with the larger tires.
Lead, follow, or get out of the way
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Marv
Dodge Dakota
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8/31/2007
23:20:08
| RE: Speedometer Need Help
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Never thought a tech with a DRBIII tool changing the rear ratio in the vehicle's computer to be a reflash.
I always considered a reflash as a total PCM or TCM program update/replacement.
Matter of interpretation. Nothing more.
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Kota Kid
Dodge Dakota
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9/03/2007
00:15:13
| RE: Speedometer Need Help
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You might want to think about going with a slightly lower gear than 4.10 with 33s. 4.56s would probably feel more like it should, expecially if you have a 3.9, because your not just compensating for the increased size but also for the increased weight. 33s weigh a lot more than stock 31s.
Sorry for any confusion I thought the same way Kowalski did, to me a reflash is just a option/setting change, a reprogram is what I've always called a complete "remove and replace" or update of the computer program.
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Bucket
GenII
9/12/2007
15:21:20
| RE: Speedometer Need Help
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Message:
When i swapped tires and gears my speedo was way off so i ordered this thing called accu-speed,its a tiny box i mounted in the cab and it has a dial and when you splice it into two wires in your tranny, you can turn the dial and it changes your speedo to what you want,it worked great on my truck,i just set my cruise at a certain speed like 65 and had a buddy do the same and i turned the dial until my speed matched his.and it was easy to install.And the box was a cool looking anodized aluminum about the size of a small pager.
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Gino
Dodge Dakota
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9/12/2007
20:44:07
| RE: Speedometer Need Help
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That thing is $200 + $15 shipping.
Check it yourself at
http://www.jetchip.com/products.asp?pid=14944&make=24#parts
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Bucket
GenII
9/13/2007
10:03:19
| RE: Speedometer Need Help
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Message:
Actually the one i got from Truckperformance.com for my 94 v-8 was 138.99,now i dont know how much a dealer would charge to "re-flash" your computer but figure in time to take it in and leave it there and then if you change tire size down the road theres no way your getting off for less than this "thing" i got, but my truck is manual so i dont have the shift point problems,that sounds to me like gears are in his future.
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