Parallax USB-RS232 converter (DIY ALDL ODB1 cable)

[cidium]

Lets see if I got this right.

I need to put a max chip between the OBD1 connector and the PL2303 chipset?

[antus]

Yes, thats right. The 2 transistor circuit you first tried is meant to achieve the same, and people have reported it working.. but my success has been as pictured.

[VL400]

Actually the MAX232 is not needed, the Prolific cable you have is TTL outputs so just use the resistor and diode method antus showed. Your original two transistor circuit converts RS232 into ALDL by inverting the signal and blocking any negative voltage.

[cidium]

My prolific cable has 3 wires, ground, TX and RX. So what I need to do is put a 1K resistor on the RX, a diode on the TX and connect those 2 wires into one wire and attach that to the M pin on the OBD1 port. Then hook the ground wire from the prolific cable to the pin A on the OBD1 port and all should be good to go?

[VL400]

Yeah thats all thats needed for a really basic 8192baud ALDL cable, it may get errors from electrical noise in the vehicle though.

Just make sure you have read this too .. https://pcmhacking.net/forums/viewtopi ... 592&p=6993

[cidium]

Ok, I'll make that up right now and see what happens....

[cidium]

Well, it hooked up on the first try but there were a ton of errors. The data logging isn't making much sense either, the values are way out of spec. So, I shut it down and opened up TP and connected again and same thing but no error the second time but the values are off the chart. Also the TP dash and other windows don't log any data. Just the item list window is working. What do you guys think is up with it?

[yoda69]

I've done a bit of digging, what ADX/XDF are you using>
For the 16156647 ECU I see the following information:
$94-------- 1227165 or 16156647------91-93 S10 Truck, 2.5L, L38
$D5-------- 16156647 -------------------92 S10 Truck, Astrovan 4.3L L35 CPI

Exactly what engine are you tuning?
In your earlier posts you show a $6E ADX and XDF, which won't work with this ECU from what I can see.

yoda69

[cidium]

I grabbed my ADS from the TP website, it located here ...

http://www.tunerpro.net/gmOBDI.htm

The ADS file I grabbed is the (A178)

Which is for: L35 92-94 TRUCK I contacted the author of this ADS file and he confirmed is was good for my truck, 92 S10 blazer (vin W) cpi. It's a 4.3l vortec cpi engine

But since i have no clue as to what I am doing, anything looks right to me.

All I want to do is data log my truck and find out why this beast is getting 10-11 mpg in the city~

I got a copy of the $D5, unzip it and got these files: BAWP.BIN and BAWP_HAC.SRC, what do i do with these files?

Yoda...I figured out what is going on now. The 2 pics of the interface are showing the difference between the stock image that TP uses on their website and the interface I was getting. The first image is from the TP website and the second is from my computer.

So....ummmm....back to the problem I am having with corrupt or wrong data showing in TP. One thing I did notice is the data seems to be cycling. It cycles thru a few eproms and sensor values and returns to the same spot it started at and cycles again, it does this till I close TP.

[antus]

The ADS files are the older format for TP4. TP5 can import them, but it doesnt necessarily work without a bit of additional manual modification to the communication macros. That is doable, but it might be easyer to start with TP4 and the ads you have. If that works we can help with TP5.

The bin and the src are an image of a D5 memcal that you can play with the pc in tunerpro. You still need an adx for it, though. The src is a disassembly of the code on the chip. Its for people who want to not just change the calibration but modify the code. Its not normally needed.

I suspect your issue is ads to tp5 import. I have seen similar with other ads files in TP5.