APP Codes/Reduced Power Mode
Thread Starter
Racer
Joined: Aug 2012
Posts: 272
Likes: 1
From: Orange County
APP Codes/Reduced Power Mode
Having the infamous problem with APP codes and reduced power on my 99 FRC. Been happening for a couple months now and it started out of the blue. Occurs randomly, so far I've replaced the pedal assy, replaced the throttle body, changed 2 of the ground packs to a regular connector (to also eliminate future hastle of cleaning ground packs), and gone through some of the wiring. Everything seems okay, checked under the battery by the pcm and tac module and everything looks fine down there but I'll have to go get a better look and really dig into it. Any other suggestions? Here's the codes I'm getting:
P1125 APP System
P1286 APP Sensor 3 Circuit Performance
C1278 TCS Temporarily Inhibitied by PCM
P1125 APP System
P1286 APP Sensor 3 Circuit Performance
C1278 TCS Temporarily Inhibitied by PCM
Racer
Joined: Mar 2005
Posts: 262
Likes: 3
From: Tempe AZ
Having the infamous problem with APP codes and reduced power on my 99 FRC. Been happening for a couple months now and it started out of the blue. Occurs randomly, so far I've replaced the pedal assy, replaced the throttle body, changed 2 of the ground packs to a regular connector (to also eliminate future hastle of cleaning ground packs), and gone through some of the wiring. Everything seems okay, checked under the battery by the pcm and tac module and everything looks fine down there but I'll have to go get a better look and really dig into it. Any other suggestions? Here's the codes I'm getting:
P1125 APP System
P1286 APP Sensor 3 Circuit Performance
RC1278 TCS Temporarily Inhibitied by PCM
P1125 APP System
P1286 APP Sensor 3 Circuit Performance
RC1278 TCS Temporarily Inhibitied by PCM
The smaller one is actually in the loop with the APP.
Jon
Racer
Joined: Mar 2005
Posts: 262
Likes: 3
From: Tempe AZ
By the way, GM connectors suck.
Team Owner
Joined: May 2001
Posts: 36,836
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From: Dear Karma, I have a list of people you missed.
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15-'16
Disconnect negative battery cable first.
Pull, closely inspect, and clean the APP connector that plugs into the TAC module. There are 2 connectors on the TAC module and this is one of them. It has 10 cavities (only 9 are used).
The circuit from the APP to the TAC is a dedicated circuit and it runs directly from the APP sensor to the TAC module and does not branch off or go anywhere else. Any corrosion/dirt/water/damage etc, can have a direct, adverse, effect on the very low voltages seen in this circuit.
I would recommend spraying WD-40, or similar, directly into the connector and use compressed air to blow out any excess. If this connector is damaged or suspect, it (connector and color coded wires, pins, etc) can easily be replaced for $14.00.
Also inspect the cable bundle(s) leading away from this area. This would include both the TAC module and the PCM. Look for any signs of damage from any of the nearby 7mm sheet-metal mounting screws that are used to hold the plastic closeout access panel in place.
The circuit from the APP to the TAC is a dedicated circuit and it runs directly from the APP sensor to the TAC module and does not branch off or go anywhere else. Any corrosion/dirt/water/damage etc, can have a direct, adverse, effect on the very low voltages seen in this circuit.
I would recommend spraying WD-40, or similar, directly into the connector and use compressed air to blow out any excess. If this connector is damaged or suspect, it (connector and color coded wires, pins, etc) can easily be replaced for $14.00.
Also inspect the cable bundle(s) leading away from this area. This would include both the TAC module and the PCM. Look for any signs of damage from any of the nearby 7mm sheet-metal mounting screws that are used to hold the plastic closeout access panel in place.
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
Excellent Info! Also,,,,, You need to check the fuse that powers the TAC Module. Use the test points on top of the fuse and measure each fuse test point to chassis ground and make sure that you have full battery voltage being supplied to the circuit.
The ignition switch needs to be ON when checking this voltage. You should see FULL BATTERY voltage on the fuse. When you remove the TAC connector, find the Ground wire and measure it to chassis ground and make sure that you have something close to zero ohms.
I would also look closely at the female pins in the TAC connector and make sure that none of them are damaged.
Examine the female pins on the TPS and Throttle Blade Actuator Motor female pins and make sure that they are not spread apart or damaged
Bill
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Thread Starter
Racer
Joined: Aug 2012
Posts: 272
Likes: 1
From: Orange County
Haha perfect, I have a '99
Just went under and checked the tac plugs out..The small plug has been replaced at some point, all the wires had new ends going into the plug on em. The ends all looked fine but I put some wd40 in there just in case. I did notice the wires were hanging loose and there is a metal clip for the screw right there so I tied them up and out of the way of that. Only thing I forgot to do was check the ohms for the ground. We'll see if I managed to do anything and report back
Just went under and checked the tac plugs out..The small plug has been replaced at some point, all the wires had new ends going into the plug on em. The ends all looked fine but I put some wd40 in there just in case. I did notice the wires were hanging loose and there is a metal clip for the screw right there so I tied them up and out of the way of that. Only thing I forgot to do was check the ohms for the ground. We'll see if I managed to do anything and report back
Thread Starter
Racer
Joined: Aug 2012
Posts: 272
Likes: 1
From: Orange County
No Bueno guys, did it again on my way to work as I was expecting. After I reset the battery or something, it usually happens again the 3rd day after that I drive it. Other than that it is unpredictable
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
Examine the engine wiring harness on the drivers side of the intake manifold. The harness runs along the head/intake manifold and down to the back of the engine.
Where it bends around the black metal bracket at the back of the fuel rail, it can rub/chafe and cause all sorts of weird engine issues.
Seen this cause your exact issue!
Where it bends around the black metal bracket at the back of the fuel rail, it can rub/chafe and cause all sorts of weird engine issues.
Seen this cause your exact issue!
Thread Starter
Racer
Joined: Aug 2012
Posts: 272
Likes: 1
From: Orange County
The wiring for the injectors and coils was all redone some time bac because the coils are relocated and it has a FAST on it. I've checked over em and they all look okay from what I can see unfortunately :/
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
Well,,, since, you keep having APP Sensor related DTCs, I recommend;
1. Make SURE that the APP sensor connector isn’t LOOSE, the female pins in the connectors are not damaged or spread apart.
2. If the above checks prove not to be the cause, order a new APP Sensor.
Please save the old one and see if you can dissect it and find out what goes wrong with them.
1. Make SURE that the APP sensor connector isn’t LOOSE, the female pins in the connectors are not damaged or spread apart.
2. If the above checks prove not to be the cause, order a new APP Sensor.
Please save the old one and see if you can dissect it and find out what goes wrong with them.
1st Gear
Joined: Jan 2015
Posts: 1
Likes: 0
so upset driving me nuts
same problem . had 2002 for five years and problem came with car . tried to by a factory replacement however they do not or for that matter does any after market manufacturer have the part . so i said to chevy what the hech am i supposed to do and they told me that they cant fix anytrhing that they cant replace with new. needly to say i was pissed this is not my driver but i can never drive it because of this issue . i have replaced it with a used one . but problem is back like crazy . it is intermintant and no answeres from chevy mechanics. so whats next. love the car was planning on getting ZO6 but whats the point if the issues will be same future with chevy ! so any ideas out there i am willing to try . thanks :
crazy2:
crazy2:
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
same problem . had 2002 for five years and problem came with car . tried to by a factory replacement however they do not or for that matter does any after market manufacturer have the part . so i said to chevy what the hech am i supposed to do and they told me that they cant fix anytrhing that they cant replace with new. needly to say i was pissed this is not my driver but i can never drive it because of this issue . i have replaced it with a used one . but problem is back like crazy . it is intermintant and no answeres from chevy mechanics. so whats next. love the car was planning on getting ZO6 but whats the point if the issues will be same future with chevy ! so any ideas out there i am willing to try . thanks :
crazy2:
crazy2:
Your problem is NOT unique and has an easy solution. First things first,,,,,,
,,,,,, You need to PROVIDE THE DTCs that come up when the issue is active. As soon as it goes into Reduced Power,, clear any messages by pressing RESET and get into the DTC reading mode with the DIC ,, WITHOUT turning the ignition OFF..
POST those DTCs
Last edited by Bill Curlee; Jan 24, 2015 at 10:45 PM.