So it came to mind but how simple are the obd2 systems on a cherokee? i rarely see jeeps with a check engine light and if so its something simple, But my dads truck has a check engine light and we got a code scanner recently and got it checked and came back with 15 codes and that took about a minute to read where as my jeep just to test took like 5 mins but had no codes at all. are they different or more simplified to say a toyotas system?

 

a main point of OBD2 is standardisation (in general terms)

another major point is they have many codes related to anti-pollution control

so theoretically an el-cheapo code reader can read & clear engine codes on any OBD2 car

sometimes they cannot communicate with system protocol though

 

I bought a scanner for my 97, and I didn't see much I could not do with it. Later vehicles have more codes that can be read.

 

Mine has this protocol issue. Once in awhile it throws a "manufacturer specific code" message at me and makes me go choose Chrysler from a list of manufacturers before it will give me the proper code for the issue.

Always wondered how it can be "standardized" if manufacturers are still allowed to put in their own proprietary "specific codes". Doesn't this once again make it unique rather than standardized at that point? lol

 

Pull the battery cables for 30 seconds and try again. If you get another 15 codes, the ECM is toast

 

lol that was on my dads truck my jeep took alot longer than his and came up with nothing

 

how old and cheap is your OBD2 scanner?

mine is over 10yrs old,a and was cheap then, paid for itself more than 10times over, (at that time, Dealers charged $80-100 to read a code!

find it often wont read VIN, but usually read & clear engine codes
my bro-in-law reckons it wouldnt read his Toyota

I believe the situation is the scanner must do a "handshake" with the ECU, if this fails no scan can take place. It is in the interest of the makers to have a protocol that will work with their $7k scanner, not so much with a $50 homie

probably time for me to upgrade mine, constantly amazed that even some mechanics dont have one

pretty sure a Google search will give all the codes, even maker specific..some data wars going on too, mainly this newer stuff with 20+ computers
..imagine trying to fix one of them on the trail 10yrs from now

 

I worked for a vehicle telematics company for awhile and learned a lot about OBD that I did not know previously. I was really surprised at how many OBD vendors there are. Some specialize in older vehicles for mechanics and shops. Some specialize in trying to keep pace with new vehicle releases. Some specialize in coverage for manufacturer specific codes etc.
There are also many different OBD protocol variants. We happened to use a library from Innova and it was very dependent on the year, make and model of a vehicle for coverage of OBD data like coolant temp, engine RPM, vehicle speed etc.
For DTC codes specifically, there are a couple of vendors that provide a similar service for manufacturer specific DTC codes. Newer vehicles will have more manufacturer specific codes than some of the older vehicles.
The OBD bus in general is pretty simple. It's more of a "check with each module" vs. the modules streaming data onto an OBD bus. Keep in mind, OBD II did was not really mandated until the 96 model year. IT was supposed to be 95 but most US manufacturers weren't ready. So vehicles from the late 90s were at the beginning of OBDII.
I also have a mid 2000's Audi A6 and if you get a VCDS/VAGCOM (Volkwagen audi group) obd scanner you can hook that up to a PC via USB and look at all the vehicle modules, change settings, perform tests, read temps etc. all through the OBD port.
One fact that you get to pretty quickly in that business is that OBD II was primarily mandated for emissions testing. The only required data from manufactures is emissions related.
The OBD II spec provides very braid categories for DTC codes, but manufactures can put as much or as little detail into specific codes as they want. I learned a tremendous amount about and definitely looked at OBD data a lot differently after that. I have since moved to Amazon/AWS to take over the world so I don't do the vehicle stuff anymore. But it was a lot of fun testing things.

 

It's probably 8 years old but I have never had it deny me access or not read the codes. But it does make me go through the extra step for it to decipher the manufacturer specific codes.