2003 srt speedo reading incorrectly

Jlewis468

Enthusiast
Joined
Aug 3, 2022
Posts
9
Reaction score
0
Location
Florida
just purchased a 2003 SRT. I noticed when driving it home speedometer said I was doing 80 whereas my handheld GPS said I was doing 75. I’ve tested the handheld GPS in other vehicles and always found it to be accurate. Any ideas what could be causing this? Any idea of how I could have it corrected? It’s my understanding from reading other posts that the speedometer calibration comes off of the ABS brake system?? I appreciate any help. I am new to the Dodge Viper scene.
 

MoparMap

VCA National President
VCA Officer
Joined
Jan 7, 2013
Posts
2,059
Reaction score
140
Location
Kansas
I would think the only thing that could throw it off would be different sized tires. I do believe it runs off of the ABS tone rings, so it's reading directly at the wheel and gears wouldn't affect it, so the only thing left is tire diameter. What size has it got on it?
 
OP
OP
J

Jlewis468

Enthusiast
Joined
Aug 3, 2022
Posts
9
Reaction score
0
Location
Florida
Thanks for the reply. And yes I should’ve stated in the above post. Stock tire size Michelin pilots on stock wheels
 

MoparMap

VCA National President
VCA Officer
Joined
Jan 7, 2013
Posts
2,059
Reaction score
140
Location
Kansas
Do you know anything else about the car? I suppose maybe it could have had different tires on it at some point in the past and maybe someone reprogrammed it then and never changed it back, but I'm not even sure if that's a thing on these cars or not. 5 mph off isn't great, but at the same time I think it's technically within the legal limit (I thought by law they had to be within 10% or something like that), so there's always a chance that's just what it is. You might try checking it with some other devices too if possible. If you know anyone with a handheld GPS or even just some buddies with cellphones. At least gives you a few more data points.
 
OP
OP
J

Jlewis468

Enthusiast
Joined
Aug 3, 2022
Posts
9
Reaction score
0
Location
Florida
Taking it to the dealer next month I’m gonna see what they think. Taking it in for alignment. It seems strange to me
 

Members online

Forum statistics

Threads
152,214
Posts
1,674,936
Members
16,590
Latest member
jly2fast4u
Top