They plug into the obd port on the vehicle. Every vehicle after 96 has one. It has to be within 11" I believe of the steering wheel, and can not require tools to access. On our trucks, it's kinda on the driver side kick panel, up under the dash

 

Winshield in. He did a comp scan for me. Was the tps. So i replaced it. Engine is off.
the wife still having early am cold crank issue.
Anyone know where the start relay is ?? Not fire wall from what i seen n checked.
On the 96 is there a power dist box ?? I cant seem to locate it....

 

If I do break down and finally buy one, do you recommend a certain type? If I invest the money for a scan tool I would rather just buy the best one out there... One that nails down the problem and not one that "it could be this or this" kinda thing... I have a 98 4x4 Blazer.

 

Well, none of them will exactly nail down the problem. It will only tell you the codes present, it's up to you to do proper troubleshooting. I forget the brand I have, I'll post it later when I get home.

You want one that will allow you to view live data, that's very beneficial for diagnosing

 

Once you have the trouble code (DTC) go to our section on how to diagnose and correct it.

Diagnostic Trouble Codes (DTCs)

 

See this recent discussion: https://blazerforum.com/forum/2nd-ge...r-tuner-98857/

You can get cheap standalone OBDII scanners for like $30 that will cover some of the basics for reading codes, but a bluetooth dongle with a smartphone app is much more capable for about the same cost.

Most of them just give you a code to clue you in to where to start looking, and then it's up to you to research and troubleshoot. If you're willing to spend a more, there are more capable ones like this one by BlueDriver for $99 that takes some of the leg work out of it for you, using its own database to give commonly reported fixes. Pretty much none of them are capable of "nailing down" every problem though. Scan tools just read the computer, and there's just only so much the computer can tell you about the machine.


So those are some pretty cost-effective tools for enthusiasts and DIYers, but if you're dead-set on "the best one out there" pro-grade tools like the Bosch Tech 2 Pro Optima can cost $4,500 -- more than the value of many of these trucks.

 

Lets keep the discussion relevant to helping the OP with his vehicular problems and take the scan tool discussion to one of the other threads on the subject. No need to hijack someone else's thread.

Crustybob, what was the specific code that the scan turned up?

Have you checked fuel pressure & leak down? THIS POST will guide you through that process.

When was the last time a tune up was performed (plugs, wires, cap, & rotor)?

Can you describe the cold cranking issues you are experiencing? Does it turn over slow? Not turn over at all? Turn over normal, but not fire? Be as descriptive as possible since you are our eyes & ears in attempting to diagnose this issue for you.

Without more details and some sleuthing on your part, we can't help out a whole lot more.