Issues getting Datastream with WINALDL
When I open WINALDL with my cable connected, the only data I have been able to display is in the raw data tab. I get a red 1 at the top, occasionally a two or three. But never this elusive green 20. The data displayed is usually just 255. See picture attached is there something I am doing wrong? Has anyone had a similar issue? Also I am only able to get this data with key off/ engine off. As soon as the key is on the data stops being displayed completely.
1986 corvette. Built 383. 700r4. 1221765 ecu. Currently working through the tuning
Out of preference I use TunerPro but Winaldl also works fine.
Your data cable must be in the 10k mode for it to work.
Unfortunately the 1227165 ECM only transfer's data at 160 baud that around 0.6 hz.
The good news is the ECM was used for several years and is compatible with a later bin file, I have burnt a 89 bin file but with a 86 spark map, as I have iron heads, it now transfer's data at 8192 baud or around 11 hz so I get a lot faster data rate and also more data as the later bin file has more items that can be monitored.
https://obd2allinone.com/
https://obd2allinone.com/
https://reddevilriver.com/home-page/ols/products/gm-12-pin-aldl-to-usb-cable
i assume the 10k mode is with the little yellow jumper on and you take it off for regular.
The Best of Corvette for Corvette Enthusiasts
This log shows the effect of the 10k resistor (applied and open) on the Pin B voltage. The ECM must see correct voltage range in order to transmit ALDL data and to change modes.
https://datazap.me/u/tequilaboy/aldl...10-329-353-388
Important voltage levels:
;
; READ A/D AND CK DIAGNOSTIC PIN B VOLTAGE....
;
LDAA #$70 ; A/D Ch 7, (Start/Run Pwr)
JSR LF1BE ; To A/D subroutine
CMPA #40 ; 800 Mv
BCS LEA45 ; BR IF A/D LT 800 Mv, (GROUND'ED TST)
; ... else
CMPA #100 ; 2.00 VDV
BCS LEA47 ; BR IF A/D LT 2.00 VDC
; ... else
CMPA #152 ; 3.04 VDV
BCC LEA47 ; BR IF A/D GT 3.05 VDC, (ROAD TST MODE)
; ... else
BRSET L0046,$08,LEA47 ; BR If 8192 Mode in locked Mode
; ... else
ORAB #$20 ; SET b5
BRA LEA47 ;
Otherwise, check the wiring integrity/continuity of pins E and B between the ALDL connector and the ecm and also verify that pin A is ground.
Last edited by tequilaboy; Dec 11, 2025 at 08:54 AM.
This log shows the effect of the 10k resistor (applied and open) on the Pin B voltage. The ECM must see correct voltage range in order to transmit ALDL data and to change modes.
https://datazap.me/u/tequilaboy/aldl...10-329-353-388
Important voltage levels:
;
; READ A/D AND CK DIAGNOSTIC PIN B VOLTAGE....
;
LDAA #$70 ; A/D Ch 7, (Start/Run Pwr)
JSR LF1BE ; To A/D subroutine
CMPA #40 ; 800 Mv
BCS LEA45 ; BR IF A/D LT 800 Mv, (GROUND'ED TST)
; ... else
CMPA #100 ; 2.00 VDV
BCS LEA47 ; BR IF A/D LT 2.00 VDC
; ... else
CMPA #152 ; 3.04 VDV
BCC LEA47 ; BR IF A/D GT 3.05 VDC, (ROAD TST MODE)
; ... else
BRSET L0046,$08,LEA47 ; BR If 8192 Mode in locked Mode
; ... else
ORAB #$20 ; SET b5
BRA LEA47 ;
Otherwise, check the wiring integrity/continuity of pins E and B between the ALDL connector and the ecm and also verify that pin A is ground.
i just have ABCEFG
when i checked between pin a and b i got .4v key on engine off











