1995 Accord ECU as Honda OBD1 protocol test box ?

**mr.sneezy** · 10-06-2016 10:06 PM

I'm a guy from Adelaide, and I'm rewriting the work done by a guy on GitHub that converts Honda OBD1 DLC protocol to ELM327 protocol. His code works OK for the basics but I'm extending it.
I have the code working now on a Arduino module on a protoboard, and going via Bluetooth to my Android tablet running an OBDII gauge display app. However using my actual car as the code test bed sucks, as it's very inconvenient in Adelaide's winter weather to be out in the rain with laptops and crap hanging out the door

To that end I am thinking I should setup a similar bare ECU on my bench that is of the right type to be Honda OBD compatible.
I think info here on Ozhonda suggests that ECU's from a OzDM 1994 or 1995 Accord CD5 would still use Honda OBD DLC protocol like my other Honda, and so would be a cheap surrogate HOBD test ECU once powered up on the bench.
Can anyone confirm that for me before I go grab one from a wreck and try it ?
(I doubt anyone would know but hey it's free to ask

Thanks,
Martin

**ECU-MAN** · 12-06-2016 04:03 PM

All pre 2000 AUDM ECU's used the DLC port. We started to see the OBDII port after the 1998 range of cars.

The popular OBDI ECU's are from the Civic and Integra range from 1992 to 1995. Although we call the next era OBDII "post 1996" they still used the DLC port and not the true OBDII port.

Good luck with your development.

**mr.sneezy** · 12-06-2016 11:21 PM

Good to know.
I had a choice of a couple of Civic ECU's as well as Prelude, Integras and Accords (they included a P2K and a P14 ECU). In the mid nineties Civics and Prelude I could not find the DLC3 connector under the dash (which did not give me confidence) so I ended up with a POA-Q51 from a 1995 Accord. I got the ECU and loom stub plus the SCS and DLC connectors. I also buzzed out the DLC before cutting it free to make sure I know which pin it went to, and it matches data I found on the web (Russian pages).
Should have it wired up to a power supply this week hopefully and get back to the coding in comfort...

**ECU-MAN** · 14-06-2016 07:58 AM

If the car has PGMFI and was built in 1992 or later, it will have the DLC connector.

Chances are you could not find it.

The POA ECU should do the trick.

**mr.sneezy** · 18-06-2016 12:16 AM

I have made up a breakout board complete with five trim pots for simulating analogue inputs (ECT, IAT, MAP, O2, TPS) and I have got the ECU talking through the Arduino to Android via bluetooth OK with those dials displayed. Now I'm setting up Torque App to send Custom PID commands to the ECU to read other data like A/C, Brake switch & VTEC pressure switch.

The trouble is currently that apart from the A/C pressure switch it seems my OzDM POA ECU doesn't have a Brake switch input or a VTEC input, the wires are not fitted in connector D position 2 and 6.
Anyone know if the Brake and VTEC switch input was moved to another pin on the ECU or is there another reason there are no wires present ?
The car was an Auto so maybe they went to the TCM instead ?

**ECU-MAN** · 18-06-2016 05:42 PM

Do the ECU connectors match the ECU ?

The ECU will get the A/C pressure switch, only A/C Switch

VTP and BKSW should go to the ECU

**mr.sneezy** · 18-06-2016 09:11 PM

The ECU is a 37820-POA-Q51, and the most complete connector diagram and EFI wiring diagram I found so far is this one saying it's from a 37820-POA-A51, just one letter different, I found it from here. http://rusefi.com/wiki/index.php?tit...da_Accord_1995
Is that far enough out for Honda ECU's to have different looms ?

The other wires were all in correct position and the correct colour codes for the main power & grounds, sensor power and grounds, analogue inputs and the SCS, DLC and Mil.
In plug D the pin 2, 3, 5, 6, 8, 10, 12 and 16 have no loom wires, which is where the info departs from my reality.

Since I posted the question above though I have got a response from the A/C pressure switch line on plug B pin 5. It took me some Googling to find out that the pressure switch is ultimately looped from the dash switch anyway, I had assumed wrongly that it was just from the gas pressure switch alone...
So I have one line working. but would appreciate your thoughts on the possible VTS and BKSW locations ?

**Dxs** · 19-06-2016 09:02 PM

My friend is working on a 94 Accord VTi. Auto

37820-p0A-q50 is the ECU code.

If you want I can take pics of the plugs (send me a PM as I will forget this thread exists).

**mr.sneezy** · 19-06-2016 10:24 PM

Originally Posted by Dxs

My friend is working on a 94 Accord VTi. Auto

37820-p0A-q50 is the ECU code.

If you want I can take pics of the plugs (send me a PM as I will forget this thread exists).

Yep sure, if his are not there then I guess that version missed out. IIRC the wreck I took the ECU out of still had it's Vtec engine in it. I'm going back tomorrow for some EFI sensors so I'll check again, it had an auto GB though.

**ECU-MAN** · 20-06-2016 02:05 PM

While you are there, look to see if the engine has a VTP sensor, take photo's

**Dxs** · 20-06-2016 06:41 PM

**Dxs** · 20-06-2016 06:42 PM

Originally Posted by mr.sneezy

Yep sure, if his are not there then I guess that version missed out. IIRC the wreck I took the ECU out of still had it's Vtec engine in it. I'm going back tomorrow for some EFI sensors so I'll check again, it had an auto GB though.

cut the plugs and take them with you.

the pics i posted is of a auto too