Bench DTC setting conditions

Holden/Delco Tuning. ALDL, OBD 1.5. Circa 1989 to 2004.
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Bench DTC setting conditions

Postby pman92 » Wed Jun 19, 2019 10:31 pm

I've been mucking around with a project flash code reader, that basically watches the flashing of the engine light and displays the code on an easy to read display.

I'm using an 808 I have to test it out on the bench.

It works fine reading code 12, but code 12 is all I can make it flash.

I've tried shorting coolant temp, TPS, MAP, MAT signals to ground and 5v to try and make it throw a dtc. It refuses to and will only display code 12.

I've put a square wave input into the REF signal of approx 1000rpm to make it think the engine is running. I've checked injector pulse, it is pulsing the injectors with my square wave input.

The factory manual says it will log coolant temp voltage low DTC if:
- Engine is running for at least 10 seconds
- CTS voltage remains below something like 150mV

I've had my REF input going for well over 10 seconds with coolant signal shorted.

It's as if it knows it's on the bench and won't log any DTC's.

What input do I have to give it to actually make it start logging codes?
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Re: Bench DTC setting conditions

Postby Holden202T » Thu Jun 20, 2019 9:13 am

try and give it a map value of about 40kpa (resistor ?) and see if that gets it working.

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Re: Bench DTC setting conditions

Postby kojab » Thu Jun 20, 2019 9:54 am

While the A-B shorting link is in place with Ignition on new fault codes will not be generated.

Remove A-B link first.
Ignition on for 15 seconds.
Then turn off ignition.
Fit A-B link, turn on ignition and check for codes.

You don't need RPM signal. With TPS disconnected Code 22 will be generated with above procedure.

You should not have ECM permanent power connected to your ignition 12 volt feed.

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Re: Bench DTC setting conditions

Postby pman92 » Thu Jun 20, 2019 10:49 am

That makes sense
I'll try that tonight

Permanent keep alive power is seperate to my switched ignition feed
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Re: Bench DTC setting conditions

Postby pman92 » Thu Jun 20, 2019 6:55 pm

Still no go. Wont flash any code other than 12. I've literally checked wiring and tried everything, but I think I found the cause.

The memcal is one I got with a bulk lot of '808s and parts from eBay years ago. See here:
viewtopic.php?f=7&t=2690

Its an AMBX-7274.
The memcal list (https://pcmhacking.net/memcals.html) lists it as a VL Group A memcal, pre-VN release.

I'm going to have a stab in the dark and say the VL never even had a check engine light and the DTC's aren't even calibrated or activated in the tune.

Now I can I will read the BIN from the memcal and post it up here for the BIN file library at some stage. (I wouldn't of even owned a programmer back when I bought these, let alone known how to read a BIN file from and eeprom lol).
I can have a look in tunerpro and confirm my theory as well.

All this doesn't help me at the moment though because I don't have any other '808 memcals and I don't want to wreck this one because its probably a bit rare.
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Re: Bench DTC setting conditions

Postby Holden202T » Fri Jun 21, 2019 11:39 am

i have just looked at the ambx tune and its definitely got the DTC's enabled!

just on a side note, its certainly got a different VE table than a VN motor!

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Re: Bench DTC setting conditions

Postby pman92 » Fri Jun 21, 2019 7:43 pm

Interesting.
I made up an adaptor and have read the BIN off my memcal, confirmed it with the ID tool, and checked and they are definitely enabled.

The VE table is quite different to AFUA VN V8 and so is the main spark table, theres something like 15 degrees less timing on the VN in some spots.
Does anyone know if the VL had the VN heads and banana manifold etc?

I tried a '424 with VR V6 CAKF memcal on my bench setup. It had no problem logging a whole heap of codes as expected. It flashed each code 3 times before moving onto the next one. It did start with a code 12, and then 22 and so on, but I assume this is normal.

The '808 setup is wired to exactly the same switch as the '424, just with a different set of connectors wired in parallel to suit the different pin-outs (there is also a set of connectors for VS/VT 3 plug PCM's and VX/VY flash PCM's wired in parallel).

I have double and triple checked wiring. The '808 definitely has both of the permanent +12v connected and working, the ignition switch only switches the ignition wire, and all earths connected to earth. I can see the engine light stay on for approx 1 second after ignition off, so I guess that means the code is still running for that period.
I have tried multiple '808 ECU's thinking one might be faulty, but all had identical results.
It refuses to flash any code other than 12.

Once I get a chance I will make up another memcal with a $A5 or $B1 or $FB VN/VP tune and see what happens
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Re: Bench DTC setting conditions

Postby kojab » Fri Jun 21, 2019 9:48 pm

The AMBX memcal is from the VL Walkinshaw and uses a a twin throttle body manifold. The inlet manifold now days would be very hard to come by, maybe $2000 for a clean unit of more.

https://www.google.com/search?q=VL+Walk ... jEGN4WrK2M:


Just found this:

Quote Originally Posted by MR 355T View Post
Yeah I got covers and complete Airbox, rails etc included, hpc coated covers and mani base as well. They're really only worth what someone's willing to pay at the end of the day. The vl ones aren't worth nearly as much in my experience. Around 5-6 k usually.

I'm with you not that keen on the VL WALKY Manifold.

Have be watching them for a number of yrs and it seem like within the last yr they have jumped to $8500 or more.
spoke with the fella that's got one on eBay but he's saying that he's sold one for $8500 and they dont last long.
Hes firm at $8500. End Quote

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Re: Bench DTC setting conditions

Postby pman92 » Wed Jul 10, 2019 7:08 pm

I made up a new memcal and put $12P on it. It set codes as it should. So it's just the AMBX that won't set codes by just leaving ignition on it seems
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