ScanGauge - A Useful Tool

[George7941]

Not only does it point out lazy thermostats, as I mentioned in my post on lazy stats, it also can read MIL codes and clear them.

I bypassed the clutch switch on my truck because I find it annoying. I am the only one driving it, I would not pypass the switch if there were other people driving it. The PCM does not see clutch interlock switch signals and every few days throws up P0833, "clutch switch signal not present". Not a problem, I punch a few buttons on the ScanGauge when I am stopped at a light,and, voila, the code is cleared.

 

[Colt45ws]

An interesting bypass might be to relay off the reverse lights so every time you use reverse, it shorts or opens the clutch wiring. Should be enough to keep it happy.

 

[supton]

I keep my SGII on velcro in my truck, and try to keep the spare cable in the door, in case anyone "needs" me to pull codes for them. [Have Torque app for my smartphone, but the last time I went looking for the dongle it walked off...] I find my SGII to not be all that good for watching fuel economy: it'll vary an easy half gallon either way when I fill up, so I leave it alone. Apparently if I drive harder than I usually do it's out of calibration somehow...

Anyhow, when it was in my Jetta I set it to watch boost (no boost factory boost guage), and in my Tundra I have it set to watch ATF temp (factory guage is useless). Water temp, ATF temp, instant mpg and tank average. Pricey but it must be going onto 10 years old. The backlight did die but it was just some broken solderjoints, easy fix.

 

[Colt45ws]

Originally Posted By: supton
I keep my SGII on velcro in my truck, and try to keep the spare cable in the door, in case anyone "needs" me to pull codes for them. [Have Torque app for my smartphone, but the last time I went looking for the dongle it walked off...] I find my SGII to not be all that good for watching fuel economy: it'll vary an easy half gallon either way when I fill up, so I leave it alone. Apparently if I drive harder than I usually do it's out of calibration somehow...

Anyhow, when it was in my Jetta I set it to watch boost (no boost factory boost guage), and in my Tundra I have it set to watch ATF temp (factory guage is useless). Water temp, ATF temp, instant mpg and tank average. Pricey but it must be going onto 10 years old. The backlight did die but it was just some broken solderjoints, easy fix.

Yeah, Ive noticed that it reads less fuel is burned than actual when I drive hard. Its far more accurate over long highway trips than in city.
I suspect it is due to it not updating quick enough. You might stomp on the gas and it pulls an update for 5.6MPG, then next update its 8.2MPG but what about the in-between? It was counting 5.6 for that space until it updated while it was trending up... Then you let off the gas right after it updates to 9.8 and now you are getting 29MPG but its still counting 9.8 until it updates.
I don't know; thats just my theory. Maybe a better algorithm or more processing power to do a higher update rate might fix the issue.
My SGII was one of the early units and shortly after the XGauge came out, I sent it in for a firmware flash to get the XGauge functionality. When it came back it was useless because it would freeze and stop communicating within 5 minutes of startup and you had to disconnect-reconnect it to make in run again. I contacted them and they sent out a revised circuit board no problem. So, I liked that a lot.

 

[sciphi]

I've had mine for a few hundred thousand miles over two cars now. What a simple, useful tool it is. Knowing what the car is doing in real time sure helps figure out when something is going wrong.

Mine's pretty good for fuel economy. The last few tanks have been within a few tenths of a gallon.

 

[Colt45ws]

On highway trips, I have to add 1-2% on it.
Driving really hard, Ive gotten as bad as +8%.
Anymore I stop at +5% and just accept it as not being correct. Otherwise, it shows terrible (more terrible than usual) mileage.

 

[supton]

Yeah, me too: it can be +/-5% on tank average, which heck I can do based off trip odo and eyeballing the fuel guage. Fun toy that earns its keep for everything else it does, not for be dead accurate all the time on tank mpg.

 

[George7941]

I have not initialised my Scangauge for tank capacity etc because I write down in a little log book the number of litres and the mileage at each fillup. I then calculate the tank average mpg. I hope I am not missing out on Scangauge capabilities by doing this. I monitor trip averages because I find that interesting - in town trips or heavy traffic generate lower mpg. Steady cruising at 100 km/hr generates an exact 10 l/100 km

 

[flatlandtacoma]

Originally Posted By: George7941
I have not initialised my Scangauge for tank capacity etc because I write down in a little log book the number of litres and the mileage at each fillup. I then calculate the tank average mpg. I hope I am not missing out on Scangauge capabilities by doing this. I monitor trip averages because I find that interesting - in town trips or heavy traffic generate lower mpg. Steady cruising at 100 km/hr generates an exact 10 l/100 km


I believe you are missing out. You can calibrate the unit to be a lot closer to your observed mpg (or l/km in your case.) At least you can on my Scanguage II.

When you fill the tank, it's I believe. It will then display the volume of fuel it thinks you have used since the last time you reset it. If it is way off, you can adjust the number to match.

I keep the display at a midrange so it is optimistic in town and pessimistic on the highway (or is it the other way around?) Anyway, it usually averages out on a full tank pretty close if you drive a mix. I also find myself bumping the adjustment one way or the other with the seasons.

Don't try to adjust to the *exact* amount displayed on the pump every time. Not every gas pump is calibrated the same. The grade on the pavement isn't the same either. Once it is close, I won't make an adjustment unless 2-3 tanks in row came in high for example.

 

[George7941]

Ok, you have convinced me, I will do the "fillup" calibrations.

 

[DriveHard]

I have posted this here before...just an FYI

Before this year, I was all for things like this. I even went out and bought my own tool just for monitoring my vehicle while I was driving. I used it quite a bit, and still use it to pull codes, and check on general vehicle health. I used to have it plugged in ALL the time in my truck. Here is what I had.
http://www.scangauge.com/

Now…I no longer drive with it plugged in unless I am actively trying to solve a problem. I was at a week long training course at the SAE headquarters in Detroit. I was asking some questions about vehicle networks and communication, and earned myself the opportunity to meet a very high up engineer at a foreign car company. He was specifically at the SAE headquarters to meet with the heads of several insurance companies in regards to the “passive” scanning devices that you plug into your OBDII port to get a discount. The short story is…anything plugged into that port disrupts vehicle communication. The OBDII port is just an interface into the vehicle network (it’s a node on the internal vehicle bus) – think of it like a gateway. Well, different nodes on a bus have different priority. That makes sure that important messages like vehicle speed, throttle position, AIRBAGS going off, etc. has a HIGH priority, and their messages can actually kick messages of lesser important off the bus. Well, the OBDII node is the HIGHEST priority on the bus because it is supposed to be used for diagnostic purposes (ie. just in the lab or garage setting). When you plug anything into the OBDII port, that device just became more important that the computer that controls vehicle stability, your airbags, your ABS, etc. ***** was meeting with the heads of these insurance companies to urge them to NOT offer those devices to the public because it has the chance to make their cars LESS safe and cause performance issues. In talking with him, the summary was “don’t leave things plugged into your OBDII port, or you risk messing up your car.”

So…now I no longer drive around with my scanner plugged in.

 

[George7941]

When the ScanGauge is not being used to clear codes or requesting freeze frame data etc, is it not just passively monitoring data traffic on the data bus and not actually interjecting itself into the data stream?

Of course malfunctions in the circuitry of the ScanGauge like a short could take down the data bus.

 

[RoadRaceJosh]

ScanGauge and UltraGauge actively poll the ECM to gather data. My Frontier has a CAN bus. Considering the relatively wide bus bandwidth and few devices on the bus I feel that there is enough bandwidth available that my UltraGauge will not cause any problems. I have been using my UltraGauge for 6 months now and have experienced zero problems.

 

[DriveHard]

Originally Posted By: Joshua_Skinner
ScanGauge and UltraGauge actively poll the ECM to gather data. My Frontier has a CAN bus. Considering the relatively wide bus bandwidth and few devices on the bus I feel that there is enough bandwidth available that my UltraGauge will not cause any problems. I have been using my UltraGauge for 6 months now and have experienced zero problems.


How do you know your bus loading? The number of devices? Have you scanned the bus directly? AFAIK, the OBDII port is not a node on the bus that you are directly looking at the vehicle bus. The OBDII port is an access port onto the bus. When you connect, you are activating a controller that is a node on the bus, not a direct connection. You would need to find the vehicle backbone and break into it to create your own node. Then you would need to know the proprietary messaging that the vehicle network is using.

 

[IndyIan]

My Ultragauge has started making my real gauges go dead and all the warning lights go on in the Focus maybe once a week, so I've stopped using it full time. The car seems to run fine when this happens but I don't want to mess anything up.
I had a scangauge2 in it for a couple years without issue, so I think the ultragauge is the culprit.

 

[flatlandtacoma]

My scanguage II has been plugged in continuously for going on 7 years and 70,000 miles. Before that it was plugged into another for 3 years. My vehicles behave exactly the same whether it is plugged in or not. FWIW.

 

[Garak]

Well, a new can of worms in the levels of BITOG OCD has just been opened!

 

[Vikas]

All scanners (or even dumb code readers) are active devices. They do indeed send request to the ECM to gather the data. EMC "should be" able to handle the continuous requests of the data without choking itself.

NO, it is not passive scanning.

 

[DriveHard]

Originally Posted By: Vikas
All scanners (or even dumb code readers) are active devices. They do indeed send request to the ECM to gather the data. EMC "should be" able to handle the continuous requests of the data without choking itself.

NO, it is not passive scanning.


My understanding is if you have an older vehicle you may be ok, but I believe bus loading on the latest vehicles is nearing a maximum. That is why there is active development on new CAN technologies and strategies to get more info on the bus. I know the scan tool is fun to monitor, and use as a diagnostic tool, its just not worth it to leave it plugged in all the time and risk a delayed airbag, ABS activation, etc. to me and my family.

Also, its not just an ECM "chocking" on the requests...it is bus loading in general. Only one message can be sent at a time on the bus. If the OBDII scan gauge is requesting engine speed, temp, MPH, MPG, etc. at the same time the Airbag is trying to be deployed, the airbag message gets BOOTED off the bus, because it is a lower priority.

If an engineer of the caliber I talked to was willing to fly from Europe to Detroit, Michigan to warn the insurance agencies against such a device, I am guessing there is some merit to the argument.

 

[George7941]

Originally Posted By: DriveHard

How do you know your bus loading? The number of devices? Have you scanned the bus directly? AFAIK, the OBDII port is not a node on the bus that you are directly looking at the vehicle bus. The OBDII port is an access port onto the bus. When you connect, you are activating a controller that is a node on the bus, not a direct connection. You would need to find the vehicle backbone and break into it to create your own node. Then you would need to know the proprietary messaging that the vehicle network is using.


Hold on for just a minute! The OBD2 port on my 2006 Sierra is just a node on the class2 VPW network. The OBD2 port, along with PCM, BCM, SARVC, IPC, ABS, SDM and the Radio all join up at the splice pack (comb) in a star configuration. There is no interface module. In other words, pin 2 of the DLC is directly connected to the single wire class2 network.

Also, on the J1939 implementation of CAN on current HD trucks, the 2 wire CAN data bus is directly connected to the DLC. With the battery disconnected you can verify the 120 ohms across the CAN bus at the DLC. Again there is no interface module.

These are the only two networks I deal with usually, so my knowledge is limited to these two cases. Perhaps there are instances where there is a interface module.