Reduced power proublem.
Thread Starter
Intermediate
Joined: Mar 2010
Posts: 43
Likes: 0
Reduced power proublem.
Well like my title says. My 99 has a proublem.When you start her up.Sometimes she's fine. Other's the ABS,And traction control lights are up.And won't shut off.Then while your driving,she'll go into"Reduced power". But not the"limp home" half power reduced power. Just a,shut off power to all the power to the doors,and dim lights.Along with the gauges.Other then the mph.And will randomly make the hatch pop after you've left the car...like 15 secends after.Along with that.Even when it's not in reduced power,the passanger window only works when you tap on the door pannel...witch i'm not a fan of..Sigh..On another note,Does anyone know why the passanger side running light keeps over heating,and blowing the bulb? It's pulling the same volt's as the drivers.And it has the same bulb,with the same distance from the housing.But it somehow melts the seal...over,and over,and over. It went out again today,for the 4th time...Has anybody had any of these proublems,or have any advise? I've been having a good friend,who has his masters from GM.And almost 20 years of exp looking. But it's going slow.Please,any leads will help!
Tech Contributor
Joined: Aug 2008
Posts: 2,902
Likes: 21
From: Oak Hill Virginia
Well like my title says. My 99 has a proublem.When you start her up.Sometimes she's fine. Other's the ABS,And traction control lights are up.And won't shut off.Then while your driving,she'll go into"Reduced power". But not the"limp home" half power reduced power. Just a,shut off power to all the power to the doors,and dim lights.Along with the gauges.Other then the mph.And will randomly make the hatch pop after you've left the car...like 15 secends after.Along with that.Even when it's not in reduced power,the passanger window only works when you tap on the door pannel...witch i'm not a fan of..Sigh..On another note,Does anyone know why the passanger side running light keeps over heating,and blowing the bulb? It's pulling the same volt's as the drivers.And it has the same bulb,with the same distance from the housing.But it somehow melts the seal...over,and over,and over. It went out again today,for the 4th time...Has anybody had any of these proublems,or have any advise? I've been having a good friend,who has his masters from GM.And almost 20 years of exp looking. But it's going slow.Please,any leads will help!
Please use paragraphs in your next post lol.You should start by posting your DTC Codes. You don't need an aftermarket scanner, you can pull them from the DIC. I'll post the procedure below.
The DRL blowing is a really common problem on these cars. The stock bulbs give off a TON of heat and actually cracks the plastic housing they fit up into. If you pull that housing you'll probably see a crack right above where the DRL sits. The crack allows moisture in and when moisture hits a hot light bulb...
The fix is to repair or replace the housing. The real long term fix is to also replace your stock bulbs with LED bulbs. Many vendors including JWMotoring sell them. They do not give off heat and thus will not damage your housing.
Here's the procedure for pulling your codes courtesy of Bill Curlee. After you pull them the first time clear ALL of them then drive the car a bit and see which ones come back...
POST DTCS!!!
READING YOUR Engine Diagnostic Trouble Codes (DTC)
This procedure should be carried out any time you experience a problem with your C5. Most inexpensive store bought aftermarket code readers will ONLY read power train DTC’s. Reading the DTC’s with the C5 built in code reader will allow you to read ALL the modules in the vehicle.
The Diagnostic Display Mode is entered with the following procedure:
1) Turn on the ignition but don't start the engine.
2) Press the RESET button to turn off any warning messages. (i.e. door open, trunk open ect)
3) Press and hold the OPTIONS button
4) While holding OPTIONS, press FUEL button four times within a 10 -second period.
Initially, the on-board diagnostics go into an Automatic Mode which will cycle through each module and shows diagnostic codes in a pre-set sequence: PCM - TCS - RTD - BCM - IPC - RADIO - HVAC - LDCM - RDCM - SCM - RFA. All codes will be displayed for each module. ( i.e. PCM = 4 codes) If none are present in a given module, you will see No More Codes on the display.
There are two types of diagnostic codes, Current and History designated with a letter suffix, “C” or “H”. A current code indicates a malfunction is present in the module displaying data. A history code indicates a problem existed sometime in the last 40 or 50 ignition cycles. When not accompanied by a current code of the same number, it's potential evidence of a previous problem, now resolved, that was not removed by clearing the codes. More likely it's an indication of an intermittent malfunction.
Intermittent codes are the most challenging of the diagnostics. An intermittent code may have happened once, may have happened more than once but is inconsistent or may be happening on a regular basis but not at the time the codes are displayed. History codes can also be caused by a current malfunction in a system that is not operating at the time codes are displayed. An example is the rear window defogger which doesn't operate until the Body Control Module detects engine rpm. For history codes set by a module that does not operate with the key on and engine off, a special diagnostic tool called a Scan Tester is necessary to properly diagnose the malfunction.
Once the system has displayed all modules, it goes into the manual mode which allows selection of each module using combinations of Driver Information Center buttons. Manual mode can also be entered during the automatic sequence by pressing any button except E/M. Once the display shows Manual Diagnostics, select a module by pressing the OPTIONS button to go forward or the TRIP button to go back. Once a module is selected, a code is displayed, and if more than one are present; press GAGES to go forward or FUEL to go back.
To exit the diagnostic mode at any time, press E/M. If you want to erase codes in a given module, press RESET To reset the codes once in manual mode, press and hold RESET until it displays NO CODES Press OPTIONS to go to the next module. Repeat the steps until you have reset the codes in all the computer modules.
NOTE!! Only reset the codes IF you want to - it is NOT necessary to do this. Clearing a code does not repair a problem. You are simply erasing the evidence of it in the module's memory. If you clear the code/s, and extinguish the Check Engine Light, your emissions status ready will NOT allow you to pass an emissions test until you have completed the required driving cycles. There are a few body module DTC’s that if set will prevent the module from operating properly. Once the DTC is cleared, the module will return to full function. This is not true for power train DTCs.
If you have never read and cleared your codes, there will probably be a lot of old history DTCs. It is recommended that you clear your codes and see if any come back during a driving cycle. Those are the ones that you need to concentrate on diagnosing.
Once you have the codes, the next question is: What to do with the information?
First, consult the factory service manual. Any serious C5 Do-It-Yourself owner should invest in the Corvette Service Manual of the appropriate model year. The Service Manual is really a requirement if you want to understand and work on your C5.
NOTE and a WARNING. You can read the DTCs while the engine is running. I pull mine up all the time while driving.
WARNING. Don’t become distracted while reading DTCs while your driving and cause an accident!!!!! Use common sense and drive safe.
These are some very good C5 Diagnostic Trouble Code (DTC) explanation web sites!!! They also explain how to read the DTCs
Here are some very good sites that explain what DTC mean:
http://www.gearchatter.com/viewtopic11755.php
http://www.obd-codes.com/trouble_cod...d-ii-codes.php
Make sure to include the H or C suffix when you post your DTCs!!
READING YOUR Engine Diagnostic Trouble Codes (DTC)
This procedure should be carried out any time you experience a problem with your C5. Most inexpensive store bought aftermarket code readers will ONLY read power train DTC’s. Reading the DTC’s with the C5 built in code reader will allow you to read ALL the modules in the vehicle.
The Diagnostic Display Mode is entered with the following procedure:
1) Turn on the ignition but don't start the engine.
2) Press the RESET button to turn off any warning messages. (i.e. door open, trunk open ect)
3) Press and hold the OPTIONS button
4) While holding OPTIONS, press FUEL button four times within a 10 -second period.
Initially, the on-board diagnostics go into an Automatic Mode which will cycle through each module and shows diagnostic codes in a pre-set sequence: PCM - TCS - RTD - BCM - IPC - RADIO - HVAC - LDCM - RDCM - SCM - RFA. All codes will be displayed for each module. ( i.e. PCM = 4 codes) If none are present in a given module, you will see No More Codes on the display.
There are two types of diagnostic codes, Current and History designated with a letter suffix, “C” or “H”. A current code indicates a malfunction is present in the module displaying data. A history code indicates a problem existed sometime in the last 40 or 50 ignition cycles. When not accompanied by a current code of the same number, it's potential evidence of a previous problem, now resolved, that was not removed by clearing the codes. More likely it's an indication of an intermittent malfunction.
Intermittent codes are the most challenging of the diagnostics. An intermittent code may have happened once, may have happened more than once but is inconsistent or may be happening on a regular basis but not at the time the codes are displayed. History codes can also be caused by a current malfunction in a system that is not operating at the time codes are displayed. An example is the rear window defogger which doesn't operate until the Body Control Module detects engine rpm. For history codes set by a module that does not operate with the key on and engine off, a special diagnostic tool called a Scan Tester is necessary to properly diagnose the malfunction.
Once the system has displayed all modules, it goes into the manual mode which allows selection of each module using combinations of Driver Information Center buttons. Manual mode can also be entered during the automatic sequence by pressing any button except E/M. Once the display shows Manual Diagnostics, select a module by pressing the OPTIONS button to go forward or the TRIP button to go back. Once a module is selected, a code is displayed, and if more than one are present; press GAGES to go forward or FUEL to go back.
To exit the diagnostic mode at any time, press E/M. If you want to erase codes in a given module, press RESET To reset the codes once in manual mode, press and hold RESET until it displays NO CODES Press OPTIONS to go to the next module. Repeat the steps until you have reset the codes in all the computer modules.
NOTE!! Only reset the codes IF you want to - it is NOT necessary to do this. Clearing a code does not repair a problem. You are simply erasing the evidence of it in the module's memory. If you clear the code/s, and extinguish the Check Engine Light, your emissions status ready will NOT allow you to pass an emissions test until you have completed the required driving cycles. There are a few body module DTC’s that if set will prevent the module from operating properly. Once the DTC is cleared, the module will return to full function. This is not true for power train DTCs.
If you have never read and cleared your codes, there will probably be a lot of old history DTCs. It is recommended that you clear your codes and see if any come back during a driving cycle. Those are the ones that you need to concentrate on diagnosing.
Once you have the codes, the next question is: What to do with the information?
First, consult the factory service manual. Any serious C5 Do-It-Yourself owner should invest in the Corvette Service Manual of the appropriate model year. The Service Manual is really a requirement if you want to understand and work on your C5.
NOTE and a WARNING. You can read the DTCs while the engine is running. I pull mine up all the time while driving.
WARNING. Don’t become distracted while reading DTCs while your driving and cause an accident!!!!! Use common sense and drive safe.
These are some very good C5 Diagnostic Trouble Code (DTC) explanation web sites!!! They also explain how to read the DTCs
Here are some very good sites that explain what DTC mean:
http://www.gearchatter.com/viewtopic11755.php
http://www.obd-codes.com/trouble_cod...d-ii-codes.php
Make sure to include the H or C suffix when you post your DTCs!!
Thread Starter
Intermediate
Joined: Mar 2010
Posts: 43
Likes: 0
Ok. Well i cheaked it. And i know i've had them cheaked from a handheld before,and cleared about 2 months ago.And it looks like i need to clear them again.
When i cheaked it,i stoped counting at 26...so lets hope next time i cheak there's less.
But on a side note. The car now has descided that when locked. Even when you use the key,the door may unlock. But the first thing you nodice is the dome light does/nt come on.And when you open the door. The alarme goes off.
And for the first time. I started the car up, And the stareo head would'nt turn on.So i turned the car off. And on again,it was fine again....so ya,i'll try to get those codes..
When i cheaked it,i stoped counting at 26...so lets hope next time i cheak there's less.
But on a side note. The car now has descided that when locked. Even when you use the key,the door may unlock. But the first thing you nodice is the dome light does/nt come on.And when you open the door. The alarme goes off.
And for the first time. I started the car up, And the stareo head would'nt turn on.So i turned the car off. And on again,it was fine again....so ya,i'll try to get those codes..
Burning Brakes
Joined: Apr 2009
Posts: 1,163
Likes: 4
From: Concord California
Check your cars batterey, how old, is it over 5 years. Rumor has it when the batt. goes weak, you can get all kinds of weird electrical issues. It's a start. if your batt. is older than 5 years.. Mine did it the batt., 6 years old, got errors, DIC started running codes up, I swapped out the batt. to a Sears Die Hard, all went away. Good luck.
Thread Starter
Intermediate
Joined: Mar 2010
Posts: 43
Likes: 0
I replaced the battery last year. But when the car was getting a new front bumper,and getting painted. They said they let it die about 7 or 8 times. They didn't really give me much a reason why. The charge stays at 13.8-14.1 according to the car. But the proubmels have been popping up a lot more sinse then.I might just put out the $120 and give it a shot,thanks.
I'm looking around for a corvette exspert they say lives somewhere around here.But i'm in Cookeville,Tennessee.
I'm looking around for a corvette exspert they say lives somewhere around here.But i'm in Cookeville,Tennessee.
Thread Starter
Intermediate
Joined: Mar 2010
Posts: 43
Likes: 0
Took a long time. But found the problem. The bcm is bairly putting anything out. Sinse the window motor on the passanger side has a lot of resistance dew to it being a 99. It was pulling what little it had. By unpluging the passanger door mod,the Bcm has enough to keep things working. Without the car freaking out. Till i get a new unprogramed one.
4th Gear
Joined: Mar 2010
Posts: 4
Likes: 0
I have a 2004 Z-06, supercharged. It's a beast but I have the same problem over and over. For no apparent reason the car goes into the reduced power mode and it will not run over 1000-1500 rpm in any gear. The signs come on for "Service Active Handling" and "Service Traction Control" and "Reduced Engine Power" and the engine light comes on. Sometimes when I turn the engine off it will re-set, but sometimes it won't. Its a fabulous car, but unreliable due to this issue. Can you disable the "Reduced Engine Power" prgram? What is causing this? I have had it into the sepped shop several tiems for thiis and they re-set the codes, but it continues to happen.
Thanks
Marty
Thanks
Marty
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Melting Slicks
Joined: Aug 2011
Posts: 2,423
Likes: 200
From: Atlanta GA
All of these issues sound like battery or grounding issues.
The C5 has 7 ground points. If these get corroded, all kinds of electrical gremlins will creep in and show their ugly heads.
If you drive in areas where humidity is high and your car is exposed regularly to rain or wet conditions, you can bet this problem will be more common.
Make sure that the grounding strap locations are free from corrosion, making good connection and lubricated with electrical conductivity type lube well. Might want to see how a silicon type protective lubricant can be applied as well.
Here is a You Tube video about location and how to maintain. Keep watching even though he says he has only found three.
The C5 has 7 ground points. If these get corroded, all kinds of electrical gremlins will creep in and show their ugly heads.
If you drive in areas where humidity is high and your car is exposed regularly to rain or wet conditions, you can bet this problem will be more common.
Make sure that the grounding strap locations are free from corrosion, making good connection and lubricated with electrical conductivity type lube well. Might want to see how a silicon type protective lubricant can be applied as well.
Here is a You Tube video about location and how to maintain. Keep watching even though he says he has only found three.
