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What Is A VIN Number?
History of VIN numbers in the US
First VIN System: 1949 to July 1964
The Vehicle Identification Number was originally described in ISO Standard 3779 in February 1977 and last revised in 1983. The ISO-VIN was designed to identify motor vehicles, trailers, motorcycles and mopeds and consists of three sections:WMI - World Manufacturer Identifier, which uniquely identifies the maker of the vehicle. It occupies the first three positions of the VIN, except when a manufacturer builds less than 500 vehicles per year, in which case the third digit is always a 9 and the 12th, 13th and 14th position of the VIN are used for the second part of the WMI. The WMI is described in ISO 3780.
VDS - Vehicle Descriptor Section. These 6 characters occupy positions 4 through 9 of the VIN and may be used by the manufacturer to identify attributes of the vehicle.
VIS - Vehicle Identifier Section. The last 8 characters of the VIN are used for the identification a of specific vehicle. The last four characters shall always be numeric.
ISO 3779 makes a provision for a code for the year in which a vehicle is built. When a manufacturer uses a year code, ISO recommends that the 10th position of the VIN is used.
The same applies to the use of a factory code. When a manufacturer uses a factory or plant code, ISO recommends that the 11th position of the VIN is used. In the VIN-code, capital letters A through Z and numbers 1 through 0 may be used, except the letters I, O and Q for obvious reasons. No signs or spaces are allowed in the VIN.
The European Union has issued a directive to the effect that a VIN must be used for all road vehicles in the EU member states. This directive complies with the ISO Standard but a year digit or factory code is not mandatory. Also, it is left to the choice of the manufacturer whether the VDS is actually used for vehicle attributes or not. The system only applies to motor powered vehicles with at least four wheels capable of speed above 25 km/h and trailers.
VINs in the United States
In North America, a system is used that is far more stringent than the ISO Standards but is "backward compatible." Here, the VIN is divided into four sections:The first three characters shall uniquely identify the manufacturer, make and type of vehicle (with the same exception of manufacturers that produce less than 500 vehicles). Effectively, this is the WMI. There are indeed examples of manufacturers who have more than one WMI that use the third character as a code for a vehicle category (for instance bus or truck). Just as often however this is not the case;
The second section consists of five characters (VIN positions 4-8) and identify the attributes of the vehicle. For each type of vehicle (passenger cars, MPV's, trucks, buses, trailers, motorcycles, incomplete vehicles other than trailers), different information is required. For cars, MPV's and light trucks it is required that the first two characters of this section are alphabetic, the third and fourth shall be numeric and the fifth alphanumeric. This section is the VDS in ISO 3779 but there it comprises another position of the VIN;
The third section consist of one character which is the check digit, calculated over the other 16 characters of the VIN. This character can be numeric or the letter X;
The fourth section consists of eight characters on positions 10-17 of the VIN. The last five shall be numeric for cars, MPV's and light trucks and the last four shall be numeric for all other vehicles. The first character represents the vehicle model year, the second character represents the plant of manufacture. The third through eighth characters are a sequential production number (for manufacturers producing more than 500 vehicles per year). For other manufacturers, the sixth, seventh and eight position represent the sequential production number.
This section confirms to the VIS in ISO 3779.
Note that (in the US regulations) no mention is made of WMI, VDS or VIS. Also, there is no mention of the third digit being a "9" in case of the smaller manufacturers. However, the examples I found of US WMI's of smaller manufacturers all have the 9 as third digit.
NSX VIN Interpretation
What is a Check Digit and how is it calculated?
Regulations both in the United States of America and Canada require that on the 9th position of the Vehicle Identification Number a check digit is used. In North America, the check digit is considered to be the third section of the VIN. Its purpose is to provide a means for verifying the accuracy of the VIN transcription. It is calculated as specified below, using the other 16 characters of the VIN.A numerical value is assigned to letters in the VIN. I, O and Q are not allowed so their positions are skipped. A=1, B=2, C=3, D=4, E=5, F=6, G=7, H=8, J=1, K=2, L=3, M=4, N=5, P=7, R=9, S=2, T=3, U=4, V=5, W=6, X=7, Y=8, Z=9
A weight factor is assigned to all positions of the VIN, except of course to the 9th position (the check digit itself), as follows: 1=8, 2=7, 3=6, 4=5, 5=4, 6=3, 7=2, 8=10, 10=9, 11=8, 12=7, 13=6, 14=5, 15=4, 16=3, 17=2
The numerical values of the letters in the VIN are multiplied by their assigned weight factor.
The resulting products from step 3 are added up.
The sum of the products is divided by 11. The numerical remainder is the check digit. If the remainder is 10, the check digit is the letter X. So the 9th position of the VIN will be a number 0-9 or the letter X.
Example Check Digit calculation
Sum of all products = 277
Digits 1-3: Manufacturer & Make
J = Japan
Digits 4-6: Model & Engine
NA1 = NSX 2 DR - 3.0L
Digit 7: Body & Transmission Type
1 = 2 DR Coupe - Manual
Digit 8: Trim Level/Restraint System
2 = 1999 Zanardi Edition (Coupe with Manual Steering, Dual Airbag, Active
Digit 9: Check Digit
0-9 or X
Digit 10: Model Year
M = 1991
They skip letters like "I", "O", and "Q" which could be confused with numeric digits. The 10th digit of the VIN number is an industry standard.
Digit 11: Assembly Plant
T = Tochigi, Japan
Five Digit Sequential Serial Number - Starts at 000001 at the beginning of every model year.
VIN # JH4NA1152MT001365 translates as:
For the US VIN numbers, the first 1991 car available for sale was 000063; all lower numbers were pre-production prototypes.
Cars sold outside the US have slightly different VIN number formats. For example, NSX's built for the Canadian market have their own sequence number range, starting with 800001 each year.