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A Primer on Code Readers and Scanners

Glacier991

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Code Readers and Code Scanners – how are they different? Let’s start by talking about trouble codes generated by automotive computers. The sophistication on automotive computers continues to increase. Ford started using Electronic Engine Control 20 or more years ago. They are on EEC-V now. Explorers prior to 95 (I think that’s the right year) are EEC-IV, and after that are EEC-V. [Edit - when I wrote this that was true, now we are migrating to CAN, there is a thread in this forum all about CAN]. Somewhere along the way the Society of Automotive Engineers tried to standardize the data formats, coming up with On Board Diagnostics I (OBD-I), and in 95 or so OBD-II. While this has been mostly successful, some manufacturers still have added “proprietary” codes, and some do not even use the same communication protocol (Some Asian and Chrysler). What this means for the DIY’er today is there is no guarantee that every code reader/scanner will work on 100% of the cars you may want to use it on. So, I’m going to gear this discussion towards FORD, since this IS an Explorer forum, after all.

The early Ex’s existed when Ford came out with their handheld “Star II” tester, supplanting the earlier "Star" code reader. Both are still around used on E-bay from time to time, for around $75 - 100 usually. The Star II tester could read out Fast and slow codes (more on that later) and DTC’s, including real time data. I’m not certain but I seem to recall they could provide snapshot capability (more later) as well as limited data logging, but I’m not certain. Star was a mere code reader.

During the early years the computer was arranged so you could, by shorting a certain pin on the test connector, read the codes by counting flashes on the Check Engine light (CEL), referred to as flashout codes. Then newer models of Code readers could hook up and actually provide the alphanumeric codes, you just had to refer to a book for their definition. Still newer and more expensive ones stored the codes in memory and would give the code number AND definition. Others had “emulation” capabilities for a Star tester, and finally some even allowed you to use interchangeable modules for different cars. The top end had the ability to read out 4 lines of 64 characters. Along came ODB-II and suddenly the number of parameters went up significantly, and the selection of testers followed suit. Today, in the DIY market, one of the most popular is Auto Xray, which is backwards compatible with OBD-I and provides capability to update the info inside via the internet. Actron manufacturing makes several different models, I have two of theirs, one of which is out of production and which I love. (Scantool III).[ This isn’t a pitch but I have a couple extra I have to sell in the trade/sale section if anyone is interested.] Snap-On and Mac made testers very similar to the Scantool III and they all retailed in the $500-700 range. Prices, and capabilities in the high end continue to spiral UP – the Genesis system from OTC for example is about $3000 – hardly a DIY tool.

A reader gives you trouble codes as set by the on board computer when some measured value goes out of parameters. These can be found for about $100 - $200. A scanner can do that, and also read out live data as your computer sees it – a hugely valuable resource. Some can store data, and even provide data present when a trouble code was set (snapshot as some mfgr’s call that). These, new, start around $250 to $300 and go up quickly. As you might guess I like E-bay and some good deals can be found there, but do your homework first. Actron stopped making the Scantool III and discontinued the ODB-II cartridge, but they can sometimes be found on E-bay as well. They also continue to sell the cartridges for OBD-I Ford, Chrysler and GM. Downside to that scanner is lack of support for newer cars past about 2000 but if you have a pre-2000 Ex they are terrific.

If money is tight, a code reader is not a bad way to go, but when you get a scanner, you have a goldmine of information available (sometimes so much it can be intimidating, if not confusing at first – but I highly recommend them. I also have a "breakout box" (allows you to access all the computer pins with a DVM) but with my scanner almost never have need for it except on older EEC-IV vehicles.

I’ll post some pics of my scanners tonight, and I heartily solicit input here from other scanner users. That will be what makes this thread valuable.

Happy exploring

Chris
 
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MrShorty

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I copied this over from the other thread you started. Seems more appropriate here, where you're discussing code scanners. We must have been writing at the same time, because I didn't see this thread until after I'd submitted the other response.
A scanner would be nice. My problem is that at least one (BII), if not both of my vehicles will not allow me to moniter engine data with a scanner. According to Autoxray, the BII's will only send trouble codes to the scanner, but not engine data (I can already get trouble codes with $3 voltmeter). Not sure at what point in the progression from early OBD-1 to late OBD-1 that the computer started sending data to scanners. Someone here mentioned that he's used his scanner on a '93 Taurus, but that's the earliest model that I've heard of using a scanner on. I've decided that, instead of buying an expensive scanner, to use a technique called "backprobing" where I use a DVOM to monitor sensors output. Given half a chance, I'd invest in a breakout box to simplify the process, but they are prohibitively expensive. I notice, Glacier, that you also have a '92. Have you had success using a scanner on your '92 Explorer? If I knew for sure that it would work on it, I might reconsider getting a scanner (though I still would have liked to have it work on both).
 
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Glacier991

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Ok, I promised some pictures, and am reatively new at this side of this wonderful forum <Thanks Rick> so here goes... The car I am going to use to demonstrate what a scanner can do is a 1993 Mercury Sable. Yeah it's not an Ex but it's Ford. This is still EEC-IV and early in the process, OBD-II gives you FAR more, but this gives you an idea. Let me try and start.. here's the EE-IV (in engine compartment, now passenger compartment in EEC-V and OBD-II) connector

Ok, let me make sure I am doing this right and I will continue...

(Edit) Well the pictures didn't post and I went back and read HOW to do it.. of course AFTER the fact <grrr>. Let me try in the next message, with apologies.
 
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Glacier991

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Funny, I often lament those who do not do a search first, or visit useful threads before posting... and I am guilty as charged... let me try again...

I am going to start with the use of a scanner on a 1993 Mercury Sable with a 3.0 engine. My Ex isn't around and it won't give us this much detail anyway on the scanner. <kids, gotta love em>. This an EEC-IV engine, so the list is short, but illustrative what you can get with a scanner. First, in the EEC-IV engines, the connector is in the engine compartment:

15286dscn3545.jpg


The white thing in the right hand side is the DPFE sensor. ANyway, hooked up and powered up you get prompted to enter data on the auto, new or stored ?

15286dscn3544.jpg


We set it up for a Mercury Sable, 93. 3.0:

15286dscn3548.jpg


So thusly connected we start the engine, and select it to read data:

15286dscn3549.jpg


So let's run down the short EEC-IV data list here. Mind you this Sable has 85K on it, and I suspect a vacuum leak, detect it ultrasonically but never looked hard enough to find it, it's not a driveability problem. Here we go:

15286dscn3550.jpg


We can see the brake on-off swich is "off" and the cannister purge is also non op at this point. The Engine Coolant Temp sensor is outputting .8 volts.... stay tuned:

15286dscn3551.jpg


You see that voltage translates into 173 degrees for the temp in degrees farenheit. Engine RPM is a little high, 928, but it was a hot restart, and that might be due to the IAC (later), or it might be my suspected vacuum leak. Next we see:

15286dscn3552.jpg


Fuel pressure at 6 psi, an IAC opening of 43% <hmmm, hot idle restart?> Intake air temp of 143 degrees farenheit and the associated voltage. Going on:

15286dscn3554.jpg


starting to get to the good stuff now. MAF is 1.1 volts. Upper end for IAF at idle, but remember this is a 928 RPM idle. Still makes you wonder if the MAF is getting dirty or it it is just increased airflow? We start to oxygen sesnor voltages... note them, because I took another picture a few seconds later.. One voltage above .445 volts and another below... the short term fuel trim on one is -3%, well within limits and it will bounce around as the voltages change: watch:

15286dscn3556.jpg
Healthy O2 sensors. The 2nd O2 sensor fuel trim is zero:

15286dscn3558.jpg


we see a spark advance of 23 degrees, <high idle and ok> and a transmission oil temperature of 158 degrees... not bad. Finally we get to long term fuel trim, where the computer has learned to compensate for engine wwear or bad components. At 84 K miles.. not unexpected, I'd get alarmed around 10%, we show:

15286dscn3553.jpg


6% isn't alarming. But it shows in this instance that we are compensating for a chronic slightly rich condition (minus % means rich- computer subtracts fuel, + % means lean). Hmmm, back to rethinking that suspected slight vacuum leak. Lastly we confirm that we are operating in "closed loop" meaning that the engine is using the O2 sensors to fine tune things.

Well this is getting long, and we will continue with code scanners and maybe an OBD-II scan, but I hope this lets you know the value of a scanner, even on an EEC-IV vehicle!

Happy Exploring

Chris
 
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Glacier991

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Missed the EGR numbers.

I should have noted that as this was an idle condition, in the earlier pictures the EGR numbers were zero, as they should be. This gives comfort on the EGR side of the house. It SHOULD ! I just replaced the DPFE sensor after living with a known half year of a CEL light.! Yeah I knew what it was, not a driveability problem so I was lazy. Didn't significant improve mileage either. (sigh)

Happy Exploring

Chris
 
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Glacier991

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Ok, so that was a scanner. Admitedly on a late production EEC-IV car, the displayed parameters on newer OBD-II cars is larger. If that didn't convince you, let's look now at a code reader. This is different. It just displays for you the Diagnostic Trouble Codes (DTC's) set by the computer. AS we have seen, a scanner can display growing problem areas or lead you in the right direction, even though the computer has not set a trouble code. BUT, they are cheaper (this one is under $200:

15286dscn3560.jpg


Next up is simpler, and cheaper, you simply have to be able to count and use a pencil to write down the number of flashes or tones you hear or see. These only work with EEC-IV but the price is right...under $20:

15286dscn3565.jpg


Finally, in retrospective, there is the old standby, a breakout box. This connected in between the Computer and the car's wiring allowing you to access the signals. It's not very visual like a scanner, but you can read EVERYTHING using a High Impedance (IMPORTANT) Digital VOM. Here's a couple shots:

15286dscn3562.jpg


You can see how it inserts itself into the wiring harness to the computer. A closer look at the board. It has 60 pin holes. EEC-V went to 102 as I recall. ( might be mistaken), anyway the importance of breakout boxes goes down as the computers read more and more and breakout boxes become more and more expensive:

15286dscn3563.jpg


So, with one exception, we've sort of scratched the surface of scanners and readers. That exception is maybe the most exciting thing to come along in a while: The ability to use the power of a PC or palm pilot to interface with your car. I am starting to experiment with this on Asian cars (where my scanner won't work), and my expectations are whetted but not fully met. I'll get some links for you to explore with in the next post.


Happy Exploring

Chris

ps. If there are things we should be covering, let me know.
 
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MrShorty

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My questions:
1) How much did you pay for your breakout box? Are they model/year specific, or will a breakout box fit multiple vehicles. The main thing holding me back on getting a breakout box are cost and whether or not I would need to get one or two. The alternative to a breakout box is backprobing connectors, which does come with certain risks. Also, that breakout box looks like it would be a lot easier to use.
2) Any definite answer on what year the PCM gained the capability to send real time data to a scanner? You mentioned in the other thread that you've never got your scanner to read real time on your '92, but you show it here for your '93. This suggests that it could be right in that time frame, though it may not fall exactly on the model year break.
 
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MrShorty

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I'd also like to add this link (EEC-IV test procedure this link is also included on the "Explorer Resources" page). The test procedures for Key on engine off (KOEO) and key on engine running (KOER) tests are given. It also shows how to connect an analog voltmeter up to obtain trouble codes, if you don't have a code reader. A trouble code reader should also include instructions for performing these tests, as well as a list of trouble codes. For information's sake, PCMs 1991 and earlier output 2 digit codes, '92-'95 output three digit codes. '96 and later use OBD-2 which outputs alphanumeric codes. Also, there is no option for outputing trouble codes with a voltmeter on OBD-2.

EDIT: (11 July '03) Wanted to add this little tidbit here. Went to the library the other day and was looking through the Motor service manual. They listed the codes by model year and engine. From this I deduced that, as noted above, the '91 4.0 L puts out 2 digit codes and the others output 3 digit codes. However, this isn't true for all Fords. Up to '91, all Fords put out 2 digit codes. In '94, all Ford engines started putting out 3 digit codes. In '92 and '93, some engines (e.g. 4.0 L V6) put out three digit codes while some (e.g. 2.9 L V6) continued to use two digit codes.
 
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Glacier991

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Shorty your last post was, as usual, dead on.

As it turns out the 90-96 Ford engines with Sequential Fuel Injection could put out Data stream - don't ask me why. Notice the SFI following the 3.0 L on the setup - that's why the Sable can do it. Too bad my 92 Ex cannot.

Breakout boxes basically come in 2 flavors for Fords. the 60 pin, for EEC-IV and the other one, I'm not sure if it was 80 or 102, I am thinking 102 for EEC-V. Any EEC-IV car will connect to the breakout box that has 60 pins. In fact mine is a 2nd hand OTC that was Ford "issue" to it's Dealers.. in 1980! They show up on E-bay often. I've seen em go for as high as $250 (they are about $400 new, and the EEC-V's are closer to $500 new), and as little as $125 on the internet. Me ? I was a smart shopper, and after a zillion failures, got mine for $150 and it was near mint. I think the DVOM (an Equus) was $30.

I wonder if a rundown on sensor construction and output is worthwhile, or whether this thread has run the gamut. I sense most people on here could care less about this stuff, only us auto geeks find this fascinating <g>, yet I am always learning something I can use.

Happy Exploring

Chris

ps. One downside to a breakout box is that the PCM connector can be a B*tch to take apart on some cars the first time.
 
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Glacier991

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Errata

As I was looking at the pics I realized what I identified as fuel pressure was not that at all, but Fuel Injector pulse width in milliseconds (a far more useful parameter). The computer adjusts fuel loading by adjusting the "on" time for injectors, known as pulse width. Sorry if that caused any confusion for the eagle eyed among you.

Happy Exploring

Chris
 
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MrShorty

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You got me to rethink getting a breakout box. I don't want to spend $400, though, so I'll try to get a second hand one. What should a breakout box come with to be complete? Your picture shows a box with built in cables. Is that all it needs?
 
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Glacier991

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Yeah, the classic breakout box comes as one unit, the pinout board and the cabling. They are attached, and the cabling is like an umbilical. Certain cars in certain years needed some adapters I think (emphasize think) the Mazda MECS system needed an adapter. There are also other adapters for other systems, like ABS etc... If you are interested I can show you a few in a follow up post. The major manufacturers were OTC, who also did Ford Rotunda, and Thexton. They are same same if you ask me. If you are willing to tkae the time to do it, you can probably get one off e-bay for under $200. It is sometimes amazing how inexpensive these type of things can be on e-bay.

Happy Exploring

Chris
 
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RLBurkett

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Laptop as Scanner?

Has anyone used a laptop to read computer codes and info? I have started to gather connectors, etc to build laptop interface. I would be interested in what others have done and what kind of data and functionallity you can get using this type of setup...

Bob
 
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Glacier991

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RL.... I think this is the logical place for the DIY enthusiast... your own computer driven interface. As the auto maunfacturers start to go more and more to multiplexing (lotsa signals on a single wire - saves em money in wiring) the PC starts to look better and better. Your Com port on your puter is probably a multiplexed port already!

I am exploring this, and so far haven't had a lot of opportunity. I'm excited at the possibility, but I think the market is new. I sincerely believe if people knew how much data there is to mine from their car's computer system they'd be more excited. I cannot tell you how many posts on here I have looked at, wishing I could hok up a computer scanner to help eliminate false leads. Believe me, in the end, someone will get very rich with a great and reasonable inexpensive PC hookup.

Here are some links:

http://www.autotap.com
http://www.auterraweb.com
http://scantool.net

The last link above is what I have, I'll post a performance use if anyone is interested..

http://www.baumtools.com/

Probably the best (and most expensive but a harbinger of what's ahead) is this one. If I was only rich! Lok at this:
https://bd2jt.securesites.com/scantool/data/scantool.htm
yet another:

http://www.mainlineauto.com.au/products/ferret/Handheld/F392/f392.htm

I know there are others and new additions daily. Go to google.com and enter OBDII and PC and check em out.

Happy Exploring

Chris
 
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MrShorty

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Glacier991

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WOW! a close 2nd the the Ease Diagnostics PC system, and a LOT less. Impressive.

Happy exploring

Chris
 
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SVO LOU

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Could you tell me which code-scanner that is in the first few pics? What should I expect to pay and where? For the life of me I can't find it. ;)
Excellent write-up/info.

Lou.
 
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lonestar

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Nice rigth up. All I have is that cheapo yellow scantool that I use for my EEC-IV cars. I am interested in getting a new scanner when I decide to buy a newer OBD-II car. Like you say, they look confusing and intimidating. By the time I figure out the scanner, I may be looking for a new car.

Do newer OBD-II scanners also read out simple trouble codes for faulty sensors? Or do you have to decipher the streaming data?

I have been searching for a high idle problem with a 88 Escort. Replaced and tested TPS and ISC. Weird part is I can flick ignition and idle returns to normal. I beleive this is prior to streaming data, so I don;t believe a newer scan tool will give me any additional information, other than trouble codes.
Dead Link Removed
 
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