[bwilson4web]

Thanks to w2co and friends, my new OBD pig-tail adapter works:


Features

• Passes only ISO 9141 signals K and L, ground and B+ to scanner
• Connects Ts, Tc and chassis ground to miniature audio plug to trigger two-code flash or error code clearing

ISO 9141 Signals

The pig-tail keeps any extra signals from the NHW11 diagnostic plug from the OBD scanner. This reduces noise to the OBD scanner and protects the NHW11 from OBD signals that might spike or confuse the vehicle. The following table shows the signals passed:

pin	signal
4	chassis ground
5	signal ground
7	ISO 9141, K-line, data signal
15	ISO 9141, L-line, data is active signal
16	battery voltage, 12 V

No other signals pass between the scanner and vehicle.

This pig-tail solves the problem of Auto Enginuity inducing false codes. It also stopped the mystery hangs.

Since the ZVW30 uses a different pair of signals, I'm planning to add a 4-pole, double throw, slide switch so it can work with both the NHW11 and ZVW30. It is very likely that the ZVW30 and NHW20 are using the same signals.

Code Flash and Clear

There are two signals used to trigger flash of the two-digit error codes; Tc, triggers flashing the error codes, and; Ts clears the code when tied to chassis ground. The mini audio jack connects to a momentary toggle switch, (on) off (on). This allows reading major error codes when an OBD scanner is not available or does not have enough support to read all codes:

pin	signal
4	chassis ground
13	Tc tied to ground causes ECUs to flash two digit codes
14	Ts tied to ground causes ECUs to clear codes

These two signals are documented for the ZVW30 and probably work on the NHW20. This may be a universal code reader for all North American Prius.

I built this one from junk box parts but if anyone would like one, send me a PM and based upon current parts costs, I'll work up the price. Currently, these look to be ~$50-75 or 'roll your own.'

Bob Wilson

[jdenenberg]

Nice work Bob. Have you passed this information to the autoenginuity folks?

JeffD

[bwilson4web]

Hi,

This is what I shared:

Auto Enginuity in "auto mode" induces false, ABS codes, and hangs frequently. I have built an ISO 9141, pig-tail, that solves these two problems by passing only:

pin 4 - chassis ground
pin 5 - signal ground
pin 7 - ISO 9141, K-line
pin 15 - ISO 9141, L-line
pin 16 - battery voltage, 12 V

In particular, this means two, Toyota signals are no long connected to the ProLine:

pin 13 - Tc that triggers flashing of the two-digit codes when tied to ground
pin 14 - Ts that clear codes

http://hiwaay.net/~bzwilson/prius/auto_400.jpg

These two signals are routed via a mini audio jack so a single-pole, double-throw, momentary switch, (on) off (on), can select which of these built-in to the NHW11 model Prius, modes to use.

Their support staff leaves a lot to be desired. Regardless, I'm now in a position to capture and analyze the layer 2, ISO 9141 protocol, on the K and L lines and validate their output.

Bob Wilson

[jdenenberg]

Bob,

Have you looked at the Rennacs code reader (PC software with their USB interface) from New Zealand?

Jeff

[GeorgiaHybrid]

Bob,

If you need to use something that can run several PID's at the same time, you are more than welcome to grab my Snap-on Modis. It has all of the cabling for OBD I and OBD II. and will read the battery state of charge, read the individual battery modules, MG1 and MG2 rpm, amp draw, etc. It is a little bulkier than the normal code readers but then again, it does a little extra too....

[bwilson4web]

Thanks for the offer. I have a Graham miniscanner and ScanGauge II which give accurate if somewhat limited data. The AutoEnginuity does a good job on just about everything except MG1 torque. But I have a plan to address that problem.

Thanks again, this is the type of collaboration that I so love in the hybrid community.

Bob Wilson