GM ECM: Vats

Thu Jun 13 21:49:25 GMT 1996

Text item: 

>>>have one of 15 resistance values. When five volts is
>>>applied to that resistor one of fifteen voltage values results
>
>I beg to differ my good man. While installing the '89 350 TPI into my '58, I
>had to crack the VATS enigma.  What I found out was that the resistor in the
>key provided a voltage to the VATS module. The VATS module would then send
>about a 30hz signal to the ecm to say "a-okay". The ecm would then allow the
>injectors to fire.
>>>The older ones
>>>used a separate VATS module which makes life easier.
>
>No info on the newer units. I was told they use a 40hz signal with a module.
>
>
>Good luck, and keep us informed.
>
>GMD
>
>Hi George
>Tnx for info:
>I am very sure you are right for 89 90. However I will do some
>investigating for newer models. My gm parts book stops listing a
>module for 90 later. Of course this doesn't mean any vats module
>GM might not be selling it.
>Curious I am as to why you simply didn't use module and resistor.
>I guess it wouldn't be very neat in a classic. The modules that
>Ecklers and others sell are quite tacky.
>Well I will be facing this when I help my friend install
>the new LT1 in his four runner. I hope he got everything as I told
>him to do.
>My test setup will probably use a older tpi but I suppose
>I can play with different ECMs as I am amasing quite a collection.
>Will keep you informed.
>Tnx again George:
>:peter
>

I just hate to see you struggle with this so...  

this works for 93--95 GM ECU's, no guarantees

--WW

400Bh   DB 0xxh   ;
                  ;
                  ; b7 1 = DE-LATCH
                  ; b6 1 = MAT SENSOR
                  ; b5 1 = 180 DEG OFFSET 
                  ; b4 1 = ASDF CRANK

                  ; b3 1 = ACCEL ENRICH LMT OPTION  
                  ; b2 1 = SYNC FUEL AT IDLE (TBI)
                  ; b1 1 = AIR MANAGE 
                  ; b0 1 = CPI/PFI MODE

400Ch   DB 0xxh   ;
                  ;
                  ; b7 1 = CAN PURGE
                  ; b6 1 = CONDITIONAL INT R/S ON BLM CELL CHNAGE
                  ; b5 1 = INT R/S ID ACELL ENRICH
                  ; b4 1 = INT RESET IN BLM CELL CHANGE
                  ; b3 1 = ASDF 
                  ; b2 1 = CRANK FUEL ALL INJ'S EACH DRP
                  ; b1 1 = ERR 44/45 BLM LMT
                  ; b0 1 = SYNC MAP SENSOR READS

400Dh   DB 0xxh   ;
                  ;
                  ; b7 1 = SINGLE PASS EGR TEST
----->>>>>>>>>>>>>; b6 1 = VATS
                  ; b5 1 = USE L4479 TBL FOR %EGR
                  ; b4 1 = EGR = 0 AT IDLE
                  ; b3 1 = OPN LP FUEL DISABLE EGR
                  ; b2 1 = BACK PRESS EGR
                  ; b1 1 = LINEAR EGR/ 0 = EVRV EGR
                  ; b0 1 = USE TBL L4BA9 FOR CLS LP AFR

400Eh   DB 0xxh  ;
                 ;
                 ; b7 1
                 ; b6 1
                 ; b5 1 = LATCH ERR 45
                 ; b4 1 = USE L4968 WITH ASYNC FUEL DELIVERY
                 ; b3 1 = CPI MANAFOLD TUNE
                 ; b2 1 = SHIFT LIGHT ENABLE 
                 ; b1 1 = ????
                 ; b0 1 

400Fh   DB 0xxh  ;
                 ;
                 ; b7 1 = MAN, (0 = TCC)
                 ; b6 1 = TCC
                 ; b5 1 
                 ; b4 1 = CONV OVER HEAT PROTECTION
                 ; b3 1 = BURST KNOCK RETARD
                 ; b2 1 = A/C CLUTCH CNT'L, 0 = CPI TUNE
                 ; b1 1 
                 ; b0 1 = 1 DO RPM/MPH LMT, (GOV'R OPT)

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Subject: Re: GM ECM: Vats
From: pfenske at direct.ca (peter paul fenske)
To: diy_efi at coulomb.eng.ohio-state.edu
Date:      Thu, 13 Jun 1996 09:37:16 -0700
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