vs manual ecu

Holden/Delco Tuning. ALDL, OBD 1.5. Circa 1989 to 2004.
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Re: vs manual ecu

Postby djbrooksy » Sun Jul 03, 2011 11:32 pm

if your mates 728 pcm is a manual pcm then the problem is not the same as mine
but if its a auto pcm then yes your in the same boat as me



what pins is the ecu lokking at for the VSS with the getrag box?
is it sill c6 and d5 as i can live without my ABS for a bit
i will just use one of the wheel sensors till i get it sorted

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Re: vs manual ecu

Postby djbrooksy » Thu Jul 07, 2011 12:29 pm

So a bit of a update
I have worked out the PPK for the the ABS sensor for the rear wheel
Changed the setting in one of the t5 bins and checked the getrag flag.
on the weekend I will change the wiring back and will feed the ABS sensor
to the pcm and see how I go

I have all so been playing with a PC soundcard scope so I might start playing on the
Bench and see if I can't get to the work out the problem with auto pcm
Last edited by djbrooksy on Thu Jul 07, 2011 6:13 pm, edited 1 time in total.

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Re: vs manual ecu

Postby VL400 » Thu Jul 07, 2011 3:19 pm

VT PCM is happy reading the T5 square wave speed sensor signal and showing vehicle speed but the VS have not got working yet (flags look correct in the bin, manual option and not getrag). U5 is a inverting buffer and the diode is a zener to clamp it to 5v.

EDIT: T5 Manual VSS works fine now :) ADX problem, the VSS item was not associated with any command :lol: Will work out the exact components needed as the U5 buffer needs > 4.2v as a high. Using 10k resistors and a 5.1v zener does not work.

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Re: vs manual ecu

Postby antus » Thu Jul 07, 2011 3:27 pm

Nice one! :thumbup: That'll help quite a few people out!
Have you read the FAQ? For lots of information and links to significant threads see here: viewtopic.php?f=7&t=1396

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Re: vs manual ecu

Postby VL400 » Thu Jul 07, 2011 4:06 pm

See this post for updated conversion info .. viewtopic.php?f=7&t=1377&p=15740#p15740

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Re: vs manual ecu

Postby djbrooksy » Thu Jul 07, 2011 6:34 pm

you sir are the man
i need to change a few things on mine then i should be good to go

i now feel for anyone that has payed the price for a vs manual pcm


thank you vl400 for the help :punk: :punk: :punk: :punk:
and thanks anyone that gave input to any of the threads that i have linked to

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Re: vs manual ecu

Postby VL400 » Thu Jul 07, 2011 6:45 pm

Keep me updated on how it works out :thumbup: The #2 resistor was the one stopping mine working when it was 10K, 3K3 was one I had on hand and works ok. If you find the VSS signal ends up being a bit of a problem from electrical noise then adjust the value of #1 capacitor - dont go above 0.01uF as the VSS signal is ~400Hz max, 0.01uF gives about a 1.5Khz roll off low pass filter so the edges are being knocked off the signal at high speeds.

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Re: vs manual ecu

Postby djbrooksy » Sat Jul 09, 2011 10:19 am

im sill not having much luck

have changed #2 to a 3k3 and #1 to a 0.01uf
i have been down to jaycar and got some 5.1v zener diodes there not smd
but i cant see how that would matter everything checks out fine with the DMM

even tryed a second 728 pcm jusst incase i cooked u5 on the 672 with the wrong parts


the speedo works so the VSS must be working and its going to D2 with the speedo wire spliced into it

what can i be doing worng or what have i missed :(

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Re: vs manual ecu

Postby VL400 » Sat Jul 09, 2011 11:05 am

My testing was on the bench using a 12v square wave so must not be the same as the VSS :( The #1 cap is just to filter the signal so dont worry about that for now. The zener is important though as its protecting the buffer chip as there should be 12v on the VSS wire.

As a test, grab a multimeter and measure the voltage on pin D2 when not moving. Then measure on the two pads...
VSSMod_2.jpg
VSSMod_2.jpg (88.78 KiB) Viewed 3268 times


The inverse pad should always be the opposite of D2, and either 0v or 5v. The other gets clamped by the zener. So can remove the VSS and put 12v on D2 and measure the voltage on the pads. The non inverting side must be pretty close to 0-5v for the buffer chip to get a valid high and low signal - which you can check on the inverting side as 0v when there is 12v on D2. Gnd D2 and should see 5v on the inverting pad - there is a pull-down resistor so should not need to gnd D2 to get 5v on the pad though.

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Re: vs manual ecu

Postby djbrooksy » Sat Jul 09, 2011 1:49 pm

can i just power the ecu on the bench and play with the VSS
or will it crack up about no sensors being hooked up

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