Hello, I just purchased a used 1990 ZR1 and the full power light in the center display does not come on when the valet switch is turned to full power. Can any one lead me in the right direction to getting this fixed. Thanks
1990 ZR1 no Full power light
- Thread starter ajcar
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Hib Halverson
Technical Writer for Internet & Print Media
Welcome to the 2G ZR1 community, "ajcar".
Without more information, it's a bit difficult to be specific but here are some possibles...
1) The bulb for the "full engine power" lamp is burned out.
2) The power key switch is faulty.
3) The secondary port throttles and the secondary injectors are not working.
Do you have the 1990 Factory Service Manual?
Without more information, it's a bit difficult to be specific but here are some possibles...
1) The bulb for the "full engine power" lamp is burned out.
2) The power key switch is faulty.
3) The secondary port throttles and the secondary injectors are not working.
Do you have the 1990 Factory Service Manual?
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No Full power light
Thank you for the reply, I have checked the bulb and it is good. I also tested the switch and that seems to be ok, all it does is goes to ground when turned on. I do have the service manual and checked the vacuum pump, when you turn the key on it runs for 3 or 4 seconds and then shuts off. If you leave the key in about a minute or two the pump will do a short burst for about a second. I have also checked the vacuum lines and do not see any major leaks. I do not know were to look next. AJ
Thank you for the reply, I have checked the bulb and it is good. I also tested the switch and that seems to be ok, all it does is goes to ground when turned on. I do have the service manual and checked the vacuum pump, when you turn the key on it runs for 3 or 4 seconds and then shuts off. If you leave the key in about a minute or two the pump will do a short burst for about a second. I have also checked the vacuum lines and do not see any major leaks. I do not know were to look next. AJ
Hib Halverson
Technical Writer for Internet & Print Media
Is the check engine light on or has it been on recently? If either, what codes were stored?
Do all the lamps on the DIC, including the full engine power lamp, come on during bulb check?
For 1990, you need two books, the Service Manual and the Electrical Diagnosis Supplement. Do you have the second book?
Do all the lamps on the DIC, including the full engine power lamp, come on during bulb check?
For 1990, you need two books, the Service Manual and the Electrical Diagnosis Supplement. Do you have the second book?
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- #6
No Full power light
Again, thank you for the reply. The check engine light has not been on. It cycles like it should when you turn the key on but I have noticed that the service ride control light does not come on also when the key is first turned on. I have taken all the bulbs out and tested them and they are ok.
I checked the codes with a paper clip both through the dash display and counting the check engine light and the dash shows no codes and the check engine light keeps showing code 12.
I do have the Electrical Diagnosis Supplement. Buy looking at the full power light circuit it looks like if there is power at the 5 amp cluster fuse and the switch goes to ground the light should come on. There is also some input from the ecm but I do not know what that is but it is also tied to ground.
Thanks again for the help. AJ
Again, thank you for the reply. The check engine light has not been on. It cycles like it should when you turn the key on but I have noticed that the service ride control light does not come on also when the key is first turned on. I have taken all the bulbs out and tested them and they are ok.
I checked the codes with a paper clip both through the dash display and counting the check engine light and the dash shows no codes and the check engine light keeps showing code 12.
I do have the Electrical Diagnosis Supplement. Buy looking at the full power light circuit it looks like if there is power at the 5 amp cluster fuse and the switch goes to ground the light should come on. There is also some input from the ecm but I do not know what that is but it is also tied to ground.
Thanks again for the help. AJ
Hib Halverson
Technical Writer for Internet & Print Media
Ok, so...bulbs are all good.
No ECM codes
But, the "service ride control" light does not come on at bulb check.
What about the "low tire pressure", "service LTPWS" and "check charging system" lights? Do they come on during bulb check?
No ECM codes
But, the "service ride control" light does not come on at bulb check.
What about the "low tire pressure", "service LTPWS" and "check charging system" lights? Do they come on during bulb check?
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Hib Halverson
Technical Writer for Internet & Print Media
Diagnosis over the Internet sometimes can be really hard, so I just want to confirm...
During bulb check, the "check charging system" light does come on but the "service ride control" light and the "full engine power" light do not come on.
Is that correct?
During bulb check, the "check charging system" light does come on but the "service ride control" light and the "full engine power" light do not come on.
Is that correct?
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- #11
Hib Halverson
Technical Writer for Internet & Print Media
Well...if during bulb check all but the service ride control and full engine power lights come on then it's not the cluster fuse.
Have you verified the ground at G106?
Have you verified the ground at G106?
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Hib Halverson
Technical Writer for Internet & Print Media
Is the service ride control light, also, still not coming on during bulb check?
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Hib. yes the ride control light is still not coming on and after reading the book this weekend the INFL REST does not come on when the key is turned to start. The book says if this light does not come on when you turn the key to run there is a problem with that system also. In one sentence they are saying if it comes on you have a problem and in the next sentence they tell you if it does not come on you have a problem. If we have 12 volts and ground along with good bulbs what else in the system am I missing? I hate to take it to GM but it looks like it is beyond my means. Thanks for the help.
Hib Halverson
Technical Writer for Internet & Print Media
Ok...so the service light for SRC is still not coming on.
First, let me say that finding a GM dealer who can effectively diagnose electronics on a 27-year old car is going to be difficult, unless it's a dealer who specializes in Corvette service and has a veteran tech on staff, You're going to be better off looking for an indpendent Corvette service shop which has experience with the electronics on later C4s.
A common problem with 90s and their SIR is the two front sensors developing corrosion underneath such that their grounding fails. The common fix is to remove the sensors, clean the frame and the bottom of the sensor brackets then put them back on. But first, perform the procedure necessary disable the SIR system then clean those sensors. Reactivate SIR and see of the light comes on at bulb check.
For the Full Engine Power light not working, if you have a DVM, go to page 8A-82-21, chart 29 and follow the diagnostic instructions.
For the SRC service light not coming on, I was unable to find a diagnostic specific to that, but I think Chart 5 on page 8A-43-8 will suffice. You need a DVM for that one, too. First, try to read SRC codes. If you can get codes write them down then clear codes. If you can't get codes, run the diagnostic. If you can get codes, do the diagnosic chart after you get them.
Just curious...how did you end up with a used 90 with so many problems?
Lastly, just for the record, I owned a C4 ZR1 for almost 20 years and did all my own service work. Sold it 18 months ago. Still have all the service manuals for C4s work on friends' C4s occasionally.
First, let me say that finding a GM dealer who can effectively diagnose electronics on a 27-year old car is going to be difficult, unless it's a dealer who specializes in Corvette service and has a veteran tech on staff, You're going to be better off looking for an indpendent Corvette service shop which has experience with the electronics on later C4s.
A common problem with 90s and their SIR is the two front sensors developing corrosion underneath such that their grounding fails. The common fix is to remove the sensors, clean the frame and the bottom of the sensor brackets then put them back on. But first, perform the procedure necessary disable the SIR system then clean those sensors. Reactivate SIR and see of the light comes on at bulb check.
For the Full Engine Power light not working, if you have a DVM, go to page 8A-82-21, chart 29 and follow the diagnostic instructions.
For the SRC service light not coming on, I was unable to find a diagnostic specific to that, but I think Chart 5 on page 8A-43-8 will suffice. You need a DVM for that one, too. First, try to read SRC codes. If you can get codes write them down then clear codes. If you can't get codes, run the diagnostic. If you can get codes, do the diagnosic chart after you get them.
Just curious...how did you end up with a used 90 with so many problems?
Lastly, just for the record, I owned a C4 ZR1 for almost 20 years and did all my own service work. Sold it 18 months ago. Still have all the service manuals for C4s work on friends' C4s occasionally.
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Thanks Hib, I will keep going looking for the problem, just having someone to tell you where to look is a big help. When I find a problem I will let you know.
The reason that I bought a car with so many problems is that I did not know it had problems. The check engine light was not on or any other lights. (Now I know why) I should have started on the forum asking questions before I bought a car. How do I disable the SIR system.
Again thanks and I will let you know what I find. AJ
Found the section that tells how to disable the SIR system
The reason that I bought a car with so many problems is that I did not know it had problems. The check engine light was not on or any other lights. (Now I know why) I should have started on the forum asking questions before I bought a car. How do I disable the SIR system.
Again thanks and I will let you know what I find. AJ
Found the section that tells how to disable the SIR system
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Hib Halverson
Technical Writer for Internet & Print Media
Actually, that the check engine light is not on is a good thing. At least you don't have to solve any ECM codes.
I'd appreciate that.
Good do that then clean the sensors and maybe the SIR will be working right.
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- #20
Hib, I got the full engine power light to come on, buy taking the display completely out of the car and then plugging it back in the light came on. I am working on the SIR system now, that light also came on. I checked the codes and got 16 and 42 which told me there was something wrong with the left front sensor and an open in the light circuit. I removed the sensor and cleaned the surface then put it back on. I tried to remove the codes but could not do that. They were both still there. Does this mean I need a new sensor? Thanks AJ
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