Techstream Question

Call me old-fashioned, but I believe in paying a fair price for another person’s effort, so I generally avoid anything pirated. For ‘diagnostics’ in my rav4 hybrid I use OBDLink with MX+, which includes OEM PIDs licensed from Toyota. As mentioned elsewhere, it is very convenient for both instantaneous gauges (I miss my gauges..... | Page 2 | PriusChat) and data logs (More on Hybrid 12V (auxiliary) battery charge control | PriusChat). One limitation is that Toyota PID names can be quite cryptic. OBDLink does not provide PID descriptions. So I peeked into Techstream, which seems intended to provide detailed PID descriptions under Data List Manager > Parameter Information. But all I see there is a copy of the PID name. Is this a limitation of all Techstream versions? Can Techstream users advise whether they see more detailed descriptions?

 

Sorry PeterJ, I have not checked in recently, so did not notice your post (thread hijack). There are many threads on many forums and commercial sites on Techstream installation, so I will not try to add to them here. Hopefully you have searched and found them by now. Read widely, the best procedure depends on your specific hardware and software combination.

To get this thread back on track, I looked in Techstream v 17.10.012, downloaded from Toyota (then loaded with patch and used without internet connection). It gives the same thing: under Data List Manager > Parameter Information there is a only a copy of the PID name. So I guess it is a limitation of all Techstream versions, at least if they are used this way.

Most PID names are self-explanatory of course, but some are quite ambiguous or cryptic. For example, how is ''Auxiliary Battery Dark Current" measured (some average, time point or minimum)? In my hands it reports various numbers from 7-30 mA on different days after overnight 'sleep' with no accessories connected, no 'smart' keyfob, vehicle locked or not. Not a critical need, but it would be helpful to know what those cryptically named PID names actually report.

 

Thanks Elektroingenieur. It is good to have another (paid) place to look. I guess that means that the information actually reported by the cryptically named PIDs is either held secret by Toyota, or charged separately by Toyota; to the added expense of those who have already paid to use the PIDs licensed by Toyota. Some countries have mandated fair access to the information needed to service and repair vehicles, but some manufacturers are working hard to restrict this from vehicle owners, and to make it slower and more expensive than the legislators intended. Hopefully it will be sorted out over time.

 

For anyone interested in the “Aux. Bat. Dark Current” PID, I think I have worked it out. At least I have understood why it gives me very different readings. I have to explain that I have put a LiFePO4 Aux. Bat. in my Rav4 Hybrid (for more capacity with a dashcam in time-lapse mode when parked), after testing and modifying the (dis)charging system to ensure that the LiFePO4 Aux. Bat. does not draw excessive charging current from the DC-DC converter. That is another story, but because Toyota does not allow owners to adjust the Aux. Bat. charging profile: (a) the system voltage often drops below the Aux. Bat. voltage when driving, and (b) I have installed an ignition-switched relay to maintain power to the dashcam while driving and a quality battery protector to cut power to the dashcam circuit if the Aux. Bat. falls below 13.0V while parked.

To complicate life, if the system voltage is below 13.0V when the ignition is turned off (which happens often with the Toyota charging profile), the battery protector cuts power to the dashcam circuit. The Toyota charging profile always jumps above 13.5V when the vehicle is in PARK for >30sec, so an owner can remember this to keep the dashcam powered. An owner can also switch the Viofo dashcam off at the front dashcam unit (which I do for the Dark Current tests).

So, have you worked it out? The relay? No, that is powered from an ignition-switched circuit. The battery protector? No, it is a Victron (MOSFET) unit that draws about 1mA. The 12V-5V converter (cigarette-lighter to USB converter) in the Viofo dashcam circuit? No, that draws only 1.7mA (though some other models that I have tested draw up to 24mA).

It is the Viofo dashcam, which draws about 20mA even when switched off at the dashcam unit! I guess this is for standby sensing, or to keep the power capacitor charged. So if the system voltage is (by chance) below 13V when the ignition is turned off, the battery protector cuts power to the dashcam circuit, and the Dark Current PID next reports 3-7mA. If the system voltage is (by chance) above 13V when the ignition is turned off, the battery protector provides power to the dashcam circuit, and the Dark Current PID next reports 23-27mA (with the dashcam switched off).

So the mystery is solved. The Dark Current PID reports either (a) a minimum or (b) a reading some time after the car enters “deep sleep” mode at around 30min after ignition off, or (c) a reading just before waking / brake relay / ignition on. I have not checked which, but for most purposes it will not matter. If it reads above 7mA after the car enters “deep sleep” mode, something (other than the car in “deep sleep”) is drawing dark current = phantom drain.

I still don’t know why the car “deep sleep” Dark Current varies from 3-7mA. From Elektroingenieur’s advice I am not confident that further payment to Toyota would solve that mystery. Perhaps the car computer sometimes expends a little power to check some electrical component? In any case, I can live with <10mA of “deep sleep” Dark Current. At that rate it should take several months of discharge to cause a problem for a 40Ah car starter battery. It is a different story with a dashcam drawing 200-300mA in time-lapse park mode. That is why I explored LiFePO4 of course.

 

After a few days of no driving (with no accessories attached) the Auxiliary Battery Dark Current readout drops to 0mA.

If that is correct, it is truly amazing, and the car should sit for a long time if necessary without draining or damaging a fully-charged auxiliary battery in good condition.

Not sure if I would try it without a serious need (and I would like to have a LiPO emergency jump start pack in the car) as there have been many complaints from owners; but it does illustrate the value for technically-oriented owners of access to Toyota PID readouts.

 

Elektroingenieur, I found DTCs but no mention of PIDs in TIS. Am I missing something? Toyota must have details of their PIDs somewhere, but they seem to regard these details as secret, even from those who pay to subscribe to TIS, or license use of the PIDs.