ALDL and accessing ECM error codes>>> - ZR-1 Net Registry Forums

ZR1Vette · 02-08-2009

After doing the plenum pull/replace injectors etc etc and all is back together and running, 'Service Engine' light remains on...not unexpected so decided to access error [trouble] codes using the protocol the Marc H and Jeffvette both describe. First thing I notice is the ALDL plug is not configured as shown from Marc's document 'The '90-93 ALDL Connector>>

Here is the ALDL plug from my MY 90 ZR...note pins E and D are missing and in the first picture F and C pins are not explained

No E & D pins normal? and what are F & C pins for?

Now the results.. got only one code>> 33 code 'MAP sensor signal voltage was too high (low vacuum) for 0.5 seconds when throttle opening was under 3%'

Any comments on this...expected after doing a plenum pull? Or is something else amiss.

Finally, how do you clear the 'Service Engine' light (stays on after engine starts..will say is still on the lift so not running as if on the road)??

Again...always appreciate any help

XfireZ51 · 02-08-2009

DIsconnect the battery for 30 sec. Then re-connect. Start the motor and see if the SES light returns. IF it does, I would go thru diagnostics outlined in the FSM for MAP v Hi.

ZR1Vette · 02-08-2009

What a good idea... 'read the FSM' which is a gentle way of saying RTFM

So to share my enlightenment, the plug I show from my ZR is correct...there are two blank [E & D] pin sites. Pin F is for TCC system which is the Torque Converter Clutch and since this connector is also used in the L98 guess they standardized since you can get an automatic in L98 variant. Pin C is for the Selective Ride Control.

I also found the test required if you throw a trouble code 33... but FSM also states this can be tripped "if you experience rough or unstable idle.." which I certainly did when I fired up the engine after the fuel injector switch out... it settle down and now runs like a kitten but I think ECM has the code in memory so I will clear.

XfireZ51 · 02-08-2009

Michael,

Was the battery connected when you did the plenum pull? Yeah those codes will come up as they did for you. That's why I usually check to see if its intermittant or recurring by clearing the ECM. Particularlyif I get a code but it seems motor is running fine.

ZR1Vette · 02-08-2009

Battery disconnected for entire time for plenum pull and injector replacement... only reconnected for the secondary actuator test.

02-08-2009	#1
ZR1Vette Join Date: Dec 2007 Location: Reston, Virginia Posts: 939	ALDL and accessing ECM error codes>>> After doing the plenum pull/replace injectors etc etc and all is back together and running, 'Service Engine' light remains on...not unexpected so decided to access error [trouble] codes using the protocol the Marc H and Jeffvette both describe. First thing I notice is the ALDL plug is not configured as shown from Marc's document 'The '90-93 ALDL Connector>> Here is the ALDL plug from my MY 90 ZR...note pins E and D are missing and in the first picture F and C pins are not explained No E & D pins normal? and what are F & C pins for? Now the results.. got only one code>> 33 code 'MAP sensor signal voltage was too high (low vacuum) for 0.5 seconds when throttle opening was under 3%' Any comments on this...expected after doing a plenum pull? Or is something else amiss. Finally, how do you clear the 'Service Engine' light (stays on after engine starts..will say is still on the lift so not running as if on the road)?? Again...always appreciate any help __________________ Michael :cheers: [I][SIZE="2"]1990 RED on RED #566[/SIZE][/I] [I][SIZE="2"]WAZOO MEMBER[/I][/SIZE]

02-08-2009	#2
XfireZ51 Join Date: May 2007 Location: Chicagoland, IL Posts: 9,708	Re: ALDL and accessing ECM error codes>>> DIsconnect the battery for 30 sec. Then re-connect. Start the motor and see if the SES light returns. IF it does, I would go thru diagnostics outlined in the FSM for MAP v Hi.

02-08-2009	#3
ZR1Vette Join Date: Dec 2007 Location: Reston, Virginia Posts: 939	Re: ALDL and accessing ECM error codes>>> What a good idea... 'read the FSM' which is a gentle way of saying RTFM So to share my enlightenment, the plug I show from my ZR is correct...there are two blank [E & D] pin sites. Pin F is for TCC system which is the Torque Converter Clutch and since this connector is also used in the L98 guess they standardized since you can get an automatic in L98 variant. Pin C is for the Selective Ride Control. I also found the test required if you throw a trouble code 33... but FSM also states this can be tripped "if you experience rough or unstable idle.." which I certainly did when I fired up the engine after the fuel injector switch out... it settle down and now runs like a kitten but I think ECM has the code in memory so I will clear. __________________ Michael :cheers: [I][SIZE="2"]1990 RED on RED #566[/SIZE][/I] [I][SIZE="2"]WAZOO MEMBER[/I][/SIZE]

02-08-2009	#4
XfireZ51 Join Date: May 2007 Location: Chicagoland, IL Posts: 9,708	Re: ALDL and accessing ECM error codes>>> Michael, Was the battery connected when you did the plenum pull? Yeah those codes will come up as they did for you. That's why I usually check to see if its intermittant or recurring by clearing the ECM. Particularlyif I get a code but it seems motor is running fine.

02-08-2009	#5
ZR1Vette Join Date: Dec 2007 Location: Reston, Virginia Posts: 939	Re: ALDL and accessing ECM error codes>>> Battery disconnected for entire time for plenum pull and injector replacement... only reconnected for the secondary actuator test. __________________ Michael :cheers: [I][SIZE="2"]1990 RED on RED #566[/SIZE][/I] [I][SIZE="2"]WAZOO MEMBER[/I][/SIZE]