Check digit

Regulations both in the USA and Canada require that the 9th position of the VIN be a check digit. 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.

1. A numerical value is assigned to letters in the VIN: 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. (Old-time programmers will recognize these values as the low-order hex digits of the letters’ EBCDIC representations.
2. A weight factor is assigned to all positions of the VIN, except the 9th position (the check digit itself):
   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.
3. The numerical values of the characters in the VIN are multiplied by the weight factors associated with their positions.
4. The products from step 3 are summed.
5. The sum from step 4 is divided by 11; the remainder is the check digit. If the remainder is 10, the check digit is the letter X.

Sample check digit calculation:

Sum of all products = 277.

277 / 11 = 25 with a remainder of 2, so the check digit is 2.

The full VIN is then JH4NA1152MT001365.

Serial numbers

In model years 1991-1996, each NSX had a serial number that was unique within that year’s US market production. Model years 1997-2005 used separate series for manual and automatic cars, with each series starting at 000001. Furthermore, 2004 NSX production was split between two plants (Tochigi and Suzuka); 2004 VINs used four separate series:

• 2004 Tochigi manual: VINs end in 4T000001, 4T000002, …
• 2004 Tochigi automatic: 4T000001, 4T000002, …
• 2004 Suzuka manual: 4S000001, 4S000002, …
• 2004 Suzuka automatic: 4S000001, 4S000002, …

Miscellaneous notes

The first 1991 NSX available for sale in the USA had serial number 000063; all lower numbers were pre-production prototypes.

The door sill plates in a US market NSX will show the final 8 characters of the car’s VIN: the positions encoding model year, plant, and serial number.

Cars sold outside the US have different VIN formats. For example, NSX models built for the Canadian market have their own serial number range, starting with 800001 each year.

History of Vehicle Identification Numbers (VINs)

First VIN System: 1949 to July 1964

The VIN for cars produced through July 1964 is merely a production serial number. It is necessary to know what model the vehicle is. No other information can be derived from the serial number.

Second VIN System: August 1964 to July 1980

Beginning in August 1964, a new system was initiated that included vehicle model and year, along with the serial number. The first two digits indicate the model, the third digit indicates the year, and the fourth through tenth digits indicate the serial number.

Due to the difficulty of differentiating ’60s vehicles from ’70s or ’80s vehicles, the following rules apply:

• 1965-1969 vehicles have a 9-digit VIN unless production exceeded 1 million, in which case the VIN is 10 digits, with the fourth digit being 1.
• 1970-1979 vehicles have a 10-digit VIN, with the fourth digit of 2 or 3.
• 1980 vehicles have a 10-digit VIN, with the third digit of A.

Third VIN System: 1981 to current models

Due to federal regulations, 1981 and newer vehicles are required to use a 17-digit VIN system. With this system, it is now possible to determine not only the year, model and serial number, but also the country of manufacture, body style, engine type, restraint system, and manufacturing plant.

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:

1. 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.
2. 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.
3. 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-Z (except I, O, and Q) and digits 0-9 may be used. 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.

In North America, a system is used that is more stringent than the ISO Standards but is backward compatible. Here, the VIN is divided into four sections:

1. The first three characters shall uniquely identify the manufacturer, make and type of vehicle (with the same exception of manufacturers that produce fewer 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;
2. 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, MPVs, trucks, buses, trailers, motorcycles, incomplete vehicles other than trailers), different information is required. For cars, MPVs 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;
3. 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;
4. The fourth section consists of eight characters on positions 10-17 of the VIN. The last five shall be numeric for cars, MPVs 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 conforms to the VIS in ISO 3779.

US VIN requirements are specified in the Code of Federal Regulations, Title 49 Part 565.

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 WMIs of smaller manufacturers all have the 9 as third digit.

[[Category:General Information]]