C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

No Check Engine Light

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Old 04-12-2018, 06:53 PM
  #21  
el ohmbre
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It not only cranked but it actually caught and ran for a second or two.

OK, That was scary. I replaced the fuse and the car runs again.

So I need to continue with the troubleshooting of the check engine light. Per the shop manual, assuming I did the probe correctly, I should be looking for Open Circuit 419, Open Circuit 39 to bulb or a bad bulb. I'll check the manual to see how to get to the light bulb and check that first. I noticed today that there is also not Parking Brake Warning light which I think there should be.

I'll also check the SnapOn scanner manual for "No Data" condition. They are probably related.

Thank you everyone for the helpful comments.
Old 04-12-2018, 09:28 PM
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Originally Posted by el ohmbre
It not only cranked but it actually caught and ran for a second or two.

OK, That was scary. I replaced the fuse and the car runs again.

So I need to continue with the troubleshooting of the check engine light. Per the shop manual, assuming I did the probe correctly, I should be looking for Open Circuit 419, Open Circuit 39 to bulb or a bad bulb. I'll check the manual to see how to get to the light bulb and check that first. I noticed today that there is also not Parking Brake Warning light which I think there should be.

I'll also check the SnapOn scanner manual for "No Data" condition. They are probably related.

Thank you everyone for the helpful comments.
What happens when you pull the fuse? Does it pulse the injectors or even crank?
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Old 04-13-2018, 02:43 PM
  #23  
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I pulled the ECM fused as suggested and the same thing happens. The engine will crank, try to catch and then die.

Remember, though that the wiring on this car may be messed up, so if this is not normal expected behavior, it may just be another wiring issue.

Right now, my main focus is to get it drive-able. Luckily it starts and once it's moving it sort of runs. However, it hesitates when starting out. Sometimes it's bad, bucks a little bit with slight backfire. That's why I was first looking for engine codes and realized there was no Check Engine light. So I tried the scanner which says No Data. Both issues lead back to the Check Engine Light bulb. I see there is also no Brake or Seatbelt telltale lights.

I think I need to get the Accessory Trim Plate removed to get to the telltales. There are four easily accessible screws but something is holding it, the shop manual shows a fifth screw coming from the driver's side. I think it's behind the I.P. Cluster Bezel which is unfortunately giving me a problem because of the extra Heads Up Display controls near the headlight switch.

Does the IP Cluster Bezel have to be removed to get the Accessory Trim Plate removed?
Old 04-14-2018, 01:48 AM
  #24  
el ohmbre
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The Check Engine bulb was burned out. I replaced it and now I have a nice Check Engine light. I ran the car, the light stayed for a while and then went off.

I tried the scanner again and the message was slightly different. Now it says "No Communication" when previously it said "No Data."

I will try jumping pins A and B tomorrow and see if the Check Engine light will do what it's supposed to do.
Old 04-14-2018, 09:58 AM
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Originally Posted by el ohmbre
The Check Engine bulb was burned out. I replaced it and now I have a nice Check Engine light. I ran the car, the light stayed for a while and then went off.

I tried the scanner again and the message was slightly different. Now it says "No Communication" when previously it said "No Data."

I will try jumping pins A and B tomorrow and see if the Check Engine light will do what it's supposed to do.

https://www.corvetteforum.com/forums...-with-ecm.html

https://www.corvetteforum.com/forums...ml?forum_id=82
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Old 04-14-2018, 12:14 PM
  #26  
el ohmbre
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Thank you very much for your help. I will read and follow those threads. I did get a code today. See below.
Old 04-14-2018, 12:21 PM
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el ohmbre
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I was able to read a code today by jumping pins A & B on the ALCL. I got code 51. I've started doing some reading on that one and it looks interesting. So far, from what I've read, I've got to find this mem-cal eprom in the ECU. I assume it's inside the little "door" on the side. I'll check the shop manual before opening it up. The descriptions of the problems sound exactly like what I'm experiencing. Very rough idle, stalling at low speed, difficult to get moving from a standing stop.

I see people reference software to run at home to "read," "program" and "tune" the eprom. I will need some sort of device though to connect the eprom to the computer, right? Also, if it's bad or the program is messed up, do I have to buy a factory replacement or are there other ways.

I still want to troubleshoot why the scanner is not working, so I'll read the threads posted above and I'll continue the research into Code 51.
Old 04-14-2018, 12:36 PM
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Originally Posted by el ohmbre
I was able to read a code today by jumping pins A & B on the ALCL. I got code 51. I've started doing some reading on that one and it looks interesting. So far, from what I've read, I've got to find this mem-cal eprom in the ECU. I assume it's inside the little "door" on the side. I'll check the shop manual before opening it up. The descriptions of the problems sound exactly like what I'm experiencing. Very rough idle, stalling at low speed, difficult to get moving from a standing stop.

I see people reference software to run at home to "read," "program" and "tune" the eprom. I will need some sort of device though to connect the eprom to the computer, right? Also, if it's bad or the program is messed up, do I have to buy a factory replacement or are there other ways.

I still want to troubleshoot why the scanner is not working, so I'll read the threads posted above and I'll continue the research into Code 51.
https://www.corvetteforum.com/forums...ty-memcal.html

https://www.corvetteforum.com/forums...-51-means.html

That could explain why you cannot scan
Old 04-14-2018, 10:59 PM
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el ohmbre
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I think it makes sense to start a new thread now since I am now able to get the Check Engine light.

I'm gong to start a new thread regarding the Code 51.

Thank to everyone for their help getting this far.



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