replaced the brake switch.
still getting the code.
lost cruise control.
whats next take it in to a tech 2?
still getting the code.
lost cruise control.
whats next take it in to a tech 2?
P0504
- Thread starter lotsofmiles
- Start date
is it just the one 'cruise' fuse?
brake & brake lights function fine.
cruise seems to be the only thing not working.
brake & brake lights function fine.
cruise seems to be the only thing not working.
Id check all of them. you would be surprised that some fuses blow and the discription has nothing to do with what is wrong but you replace them and everything works. if power gets sent back in the wrong direction it can also blow fuses that mean nothing for the actual prob.
cant find any blown fuses.
Here is the description from a GM parts guy/member at the place:
"The ECM monitors the stop lamp switch signal circuit and the TCC brake switch/cruise control release signal circuit every 100 ms. The ECM monitors the status of the stop lamp switch signal circuit and the TCC brake switch/cruise control signal circuit to see if they match when the brake pedal is pressed or released."
on a side note, the same day it threw the code I was on my way to get a trailer. When I was hooking up the 5th wheel I plugged the trailer wires into the plug in the bed. No trailer running lights. Tried the plug under the bumper, no running lights. Tried a test light, had power at the plug for the running lights
Under a load there wasnt enough of a connection to power the trailer running lights.
My bed plug is aftermarket/dealer addon. Where they tapped into the trailer wiring for the bed plug was totally corroded. I replaced all the connections at the junction point.
I have a feeloing I will have to do it again tho. I couldnt find any 10-12 gauge water proof connectors for connecting 3 - 10-12 gauge wires. So I sealed it up the best I could.
I'm guessing I might still have something shorting out or a weak connection in the trailer wiring somewhere.
700+ miles today with no cruise sucked
Here is the description from a GM parts guy/member at the place:
"The ECM monitors the stop lamp switch signal circuit and the TCC brake switch/cruise control release signal circuit every 100 ms. The ECM monitors the status of the stop lamp switch signal circuit and the TCC brake switch/cruise control signal circuit to see if they match when the brake pedal is pressed or released."
on a side note, the same day it threw the code I was on my way to get a trailer. When I was hooking up the 5th wheel I plugged the trailer wires into the plug in the bed. No trailer running lights. Tried the plug under the bumper, no running lights. Tried a test light, had power at the plug for the running lights
Under a load there wasnt enough of a connection to power the trailer running lights.
My bed plug is aftermarket/dealer addon. Where they tapped into the trailer wiring for the bed plug was totally corroded. I replaced all the connections at the junction point.
I have a feeloing I will have to do it again tho. I couldnt find any 10-12 gauge water proof connectors for connecting 3 - 10-12 gauge wires. So I sealed it up the best I could.
I'm guessing I might still have something shorting out or a weak connection in the trailer wiring somewhere.
700+ miles today with no cruise sucked
ummmm,
it looks like I can turn off the code with EFI.
So, with the way my week has been going I better ask:
If I turn off the code I'm not going to have a 8600LB run-away accelerating on its own wannabe Toyota am I?
it looks like I can turn off the code with EFI.
So, with the way my week has been going I better ask:
If I turn off the code I'm not going to have a 8600LB run-away accelerating on its own wannabe Toyota am I?
turned it off with efi.
still no cruise
so I have a short somewhere or,
I replaced the brake switch on the brake pedal. maybe the tcc brake switch?
still no cruise
so I have a short somewhere or,
I replaced the brake switch on the brake pedal. maybe the tcc brake switch?
so there is no cruise module on these things?
printed a pic off the net for the module on an lbz. No wonder I cant find it on the truck.
printed a pic off the net for the module on an lbz. No wonder I cant find it on the truck.
when you 'disable' a code with efi all it does is ghost the code. the code is still present just not setting off the mil lamp.
i know the tps is a redundant switch i wonder if the brake switch is as well.... the code is Brake Switch Circuit 1-2 Correlation
i know the tps is a redundant switch i wonder if the brake switch is as well.... the code is Brake Switch Circuit 1-2 Correlation
another switch somewhere?
.
.
I've got the test instructions from dealer. 1st thing was eliminate brake controller. did that and still no cruise.
.
.
.
I've got the test instructions from dealer. 1st thing was eliminate brake controller. did that and still no cruise.
.
DTC P0504
Circuit Description
The engine control module (ECM) monitors the stop lamp switch signal circuit and the torque converter clutch (TCC) brake switch/cruise control release signal circuit every 100 ms. The ECM monitors the status of the stop lamp switch signal circuit and the TCC brake switch/cruise control signal circuit to see if they match when the brake pedal is pressed or released.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0504 Brake Switch Circuit 1-2 Correlation
Conditions for Running the DTC
The ignition is ON.
Conditions for Setting the DTC
The status of the stop lamp switch input to the ECM, and the TCC brake switch/cruise control input to the ECM do not match for at least 2 seconds continuously, for 10 occurrences. Each time the signals match then do not match a counter increments. When the counter reaches 10 the DTC will set.
Action Taken When the DTC Sets
When DTC P0504 is set the following will occur:
</th><th rowspan="1" valign="bottom" align="center">Action
</th><th rowspan="1" valign="bottom" align="center">Yes
</th><th rowspan="1" valign="bottom" align="center">No
</th></tr> <tr> <td rowspan="1" colspan="4" valign="middle" align="left">Schematic Reference: Exterior Lights Schematics and Cruise Control Schematics
Connector End View Reference: Master Electrical Component List
</td></tr> <tr> <td rowspan="1" valign="middle" align="center">1
</td><td rowspan="1" valign="top" align="left">Did you perform the Diagnostic System Check - Vehicle?
</td><td rowspan="1" valign="bottom" align="center">Go to Step 2
</td><td rowspan="1" valign="bottom">Go to Diagnostic System Check - Vehicle
</td></tr> <tr> <td rowspan="1" valign="middle" align="center">2
</td><td rowspan="1">
</td><td rowspan="1" valign="bottom">Go to Diagnostic Aids
</td><td rowspan="1" valign="bottom" align="center">Go to Step 3
</td></tr> <tr> <td rowspan="1" valign="middle" align="center">3
</td><td rowspan="1">
</td><td rowspan="1" valign="bottom" align="center">Go to Step 6
</td><td rowspan="1" valign="bottom" align="center">Go to Step 4
</td></tr> <tr> <td rowspan="1" valign="middle" align="center">4
</td><td rowspan="1" valign="top" align="left">
</td><td rowspan="1" valign="bottom" align="center">Go to Step 5
</td><td rowspan="1" valign="bottom" align="center">Go to Step 12
</td></tr> <tr> <td rowspan="1" valign="middle" align="center">5
</td><td rowspan="1">
</td><td rowspan="1" valign="bottom" align="center">Go to Step 15
</td><td rowspan="1" valign="bottom" align="center">Go to Step 8
</td></tr> <tr> <td rowspan="1" valign="middle" align="center">6
</td><td rowspan="1">
</td><td rowspan="1" valign="bottom" align="center">Go to Step 7
</td><td rowspan="1" valign="bottom" align="center">Go to Step 10
</td></tr> <tr> <td rowspan="1" valign="middle" align="center">7
</td><td rowspan="1">
</td><td rowspan="1" valign="bottom" align="center">Go to Step 15
</td><td rowspan="1" valign="bottom" align="center">Go to Step 11
</td></tr> <tr> <td rowspan="1" valign="middle" align="center">8
</td><td rowspan="1">Test the ignition positive voltage circuit of the stop lamp switch for an open or short to ground. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?
</td><td rowspan="1" valign="bottom" align="center">Go to Step 18
</td><td rowspan="1" valign="bottom" align="center">Go to Step 9
</td></tr> <tr> <td rowspan="1" valign="middle" align="center">9
</td><td rowspan="1">Test for an open or short to ground in the TCC brake switch/cruise control release signal circuit of the stop lamp switch. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?
</td><td rowspan="1" valign="bottom" align="center">Go to Step 18
</td><td rowspan="1" valign="bottom" align="center">Go to Step 14
</td></tr> <tr> <td rowspan="1" valign="middle" align="center">10
</td><td rowspan="1" valign="top" align="left">Test the stop lamp switch signal circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?
</td><td rowspan="1" valign="bottom" align="center">Go to Step 18
</td><td rowspan="1" valign="bottom" align="center">Go to Step 14
</td></tr> <tr> <td rowspan="1" valign="middle" align="center">11
</td><td rowspan="1">Test the battery positive voltage circuit of the stop lamp switch for an open or short to ground. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?
</td><td rowspan="1" valign="bottom" align="center">Go to Step 18
</td><td rowspan="1" valign="bottom" align="center">Go to Step 13
</td></tr> <tr> <td rowspan="1" valign="middle" align="center">12
</td><td rowspan="1">Test the TCC brake switch/cruise control release signal circuit of the stop lamp switch for a short to voltage. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?
</td><td rowspan="1" valign="bottom" align="center">Go to Step 18
</td><td rowspan="1" valign="bottom" align="center">Go to Step 16
</td></tr> <tr> <td rowspan="1" valign="middle" align="center">13
</td><td rowspan="1">Test the stop lamp switch signal circuit for an open or short to ground. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?
</td><td rowspan="1" valign="bottom" align="center">Go to Step 18
</td><td rowspan="1" valign="bottom" align="center">Go to Step 14
</td></tr> <tr> <td rowspan="1" valign="middle" align="center">14
</td><td rowspan="1" valign="top" align="left">Inspect for poor connections at the harness connector of the engine control module (ECM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .
Did you find and correct the condition?
</td><td rowspan="1" valign="bottom" align="center">Go to Step 18
</td><td rowspan="1" valign="bottom" align="center">Go to Step 16
</td></tr> <tr> <td rowspan="1" valign="middle" align="center">15
</td><td rowspan="1">Inspect for poor connections at the harness connector of the stop lamp switch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .
Did you find and correct the condition?
</td><td rowspan="1" valign="bottom" align="center">Go to Step 18
</td><td rowspan="1" valign="bottom" align="center">Go to Step 17
</td></tr> <tr> <td rowspan="1" valign="middle" align="center">16
</td><td rowspan="1">Replace the ECM. Refer to Control Module References .
Did you complete the replacement?
</td><td rowspan="1" valign="bottom" align="center">Go to Step 18
</td><td rowspan="1" valign="bottom" align="center">--
</td></tr> <tr> <td rowspan="1" valign="middle" align="center">17
</td><td rowspan="1">Replace the stop lamp switch. Refer to Stop Lamp Switch Replacement .
Did you complete the replacement?
</td><td rowspan="1" valign="bottom" align="center">Go to Step 18
</td><td rowspan="1" valign="bottom" align="center">--
</td></tr> <tr> <td rowspan="1" valign="middle" align="center">18
</td><td rowspan="1" valign="top" align="left">
</td><td rowspan="1" valign="bottom" align="center">Go to Step 2
</td><td rowspan="1" valign="bottom" align="center">System OK
</td></tr></tbody></table>
Circuit Description
The engine control module (ECM) monitors the stop lamp switch signal circuit and the torque converter clutch (TCC) brake switch/cruise control release signal circuit every 100 ms. The ECM monitors the status of the stop lamp switch signal circuit and the TCC brake switch/cruise control signal circuit to see if they match when the brake pedal is pressed or released.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0504 Brake Switch Circuit 1-2 Correlation
Conditions for Running the DTC
The ignition is ON.
Conditions for Setting the DTC
The status of the stop lamp switch input to the ECM, and the TCC brake switch/cruise control input to the ECM do not match for at least 2 seconds continuously, for 10 occurrences. Each time the signals match then do not match a counter increments. When the counter reaches 10 the DTC will set.
Action Taken When the DTC Sets
When DTC P0504 is set the following will occur:
<table border="0"><tbody><tr><td valign="top"> • </td><td valign="top">The cruise control is disabled.</td></tr></tbody></table>
<table border="0"><tbody><tr><td valign="top"> • </td><td valign="top">The ECM will function as if the brake pedal is not pressed.</td></tr></tbody></table>
<table border="0"><tbody><tr><td valign="top"> • </td><td valign="top">The control module stores the DTC information into memory when the diagnostic runs and fails.</td></tr></tbody></table>
<table border="0"><tbody><tr><td valign="top"> • </td><td valign="top">The malfunction indicator lamp (MIL) will not illuminate.</td></tr></tbody></table>
<table border="0"><tbody><tr><td valign="top"> • </td><td valign="top">The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records.</td></tr></tbody></table>
Conditions for Clearing the DTC<table border="0"><tbody><tr><td valign="top"> • </td><td valign="top">The DTC will clear when the status of the stop lamp switch input to the ECM, and the TCC brake switch/cruise control input to the ECM match for at least 2 seconds continuously for both the pressed position and the released position.</td></tr></tbody></table>
<table border="0"><tbody><tr><td valign="top"> • </td><td valign="top">A current DTC Last Test Failed clears when the diagnostic runs and passes.</td></tr></tbody></table>
<table border="0"><tbody><tr><td valign="top"> • </td><td valign="top">A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.</td></tr></tbody></table>
<table border="0"><tbody><tr><td valign="top"> • </td><td valign="top">Clear the DTC with a scan tool.</td></tr></tbody></table>
Diagnostic Aids<table border="0"><tbody><tr><td valign="top"> • </td><td valign="top">Aftermarket trailer brake controllers must be disconnected before diagnosing DTC P0504 due to they could result in incorrect diagnostics.</td></tr></tbody></table>
<table border="0"><tbody><tr><td valign="top"> • </td><td valign="top">Check for intermittents and poor connections. Refer to Testing for Intermittent Conditions and Poor Connections .</td></tr></tbody></table>
<table width="95%" border="1"><tbody><tr> <th rowspan="1" valign="bottom" align="center">Step</th><th rowspan="1" valign="bottom" align="center">Action
</th><th rowspan="1" valign="bottom" align="center">Yes
</th><th rowspan="1" valign="bottom" align="center">No
</th></tr> <tr> <td rowspan="1" colspan="4" valign="middle" align="left">Schematic Reference: Exterior Lights Schematics and Cruise Control Schematics
Connector End View Reference: Master Electrical Component List
</td></tr> <tr> <td rowspan="1" valign="middle" align="center">1
</td><td rowspan="1" valign="top" align="left">Did you perform the Diagnostic System Check - Vehicle?
</td><td rowspan="1" valign="bottom" align="center">Go to Step 2
</td><td rowspan="1" valign="bottom">Go to Diagnostic System Check - Vehicle
</td></tr> <tr> <td rowspan="1" valign="middle" align="center">2
</td><td rowspan="1">
- Turn the key On, engine OFF
- With the scan tool, observe the Stop Lamp Pedal Switch parameter and TCC/Cruise Brake Pedal Switch parameter in the Powertrain, Diesel, Data Display, Eng Data Display menu.
- Press and release the brake pedal.
</td><td rowspan="1" valign="bottom">Go to Diagnostic Aids
</td><td rowspan="1" valign="bottom" align="center">Go to Step 3
</td></tr> <tr> <td rowspan="1" valign="middle" align="center">3
</td><td rowspan="1">
- With the scan tool, observe the TCC/Cruise Brake Pedal Switch parameter.
- Press and release the brake pedal.
</td><td rowspan="1" valign="bottom" align="center">Go to Step 6
</td><td rowspan="1" valign="bottom" align="center">Go to Step 4
</td></tr> <tr> <td rowspan="1" valign="middle" align="center">4
</td><td rowspan="1" valign="top" align="left">
- Turn OFF the ignition.
- Disconnect the stop lamp switch.
- Turn ON the ignition, with the engine OFF.
</td><td rowspan="1" valign="bottom" align="center">Go to Step 5
</td><td rowspan="1" valign="bottom" align="center">Go to Step 12
</td></tr> <tr> <td rowspan="1" valign="middle" align="center">5
</td><td rowspan="1">
- Turn OFF the ignition.
- Connect a 10-amp fused jumper between the ignition positive voltage circuit of the stop lamp switch and the TCC brake switch/cruise control release signal circuit of the stop lamp switch.
- Turn ON the ignition, with the engine OFF.
</td><td rowspan="1" valign="bottom" align="center">Go to Step 15
</td><td rowspan="1" valign="bottom" align="center">Go to Step 8
</td></tr> <tr> <td rowspan="1" valign="middle" align="center">6
</td><td rowspan="1">
- Turn OFF the ignition.
- Disconnect the stop lamp switch.
- Turn ON the ignition, with the engine off.
- With the scan tool, observe the Stop Lamp Pedal Switch parameter.
</td><td rowspan="1" valign="bottom" align="center">Go to Step 7
</td><td rowspan="1" valign="bottom" align="center">Go to Step 10
</td></tr> <tr> <td rowspan="1" valign="middle" align="center">7
</td><td rowspan="1">
- Turn OFF the ignition.
- Connect a 20-amp fused jumper between the battery positive voltage circuit of the stop lamp switch and the stop lamp switch signal circuit.
- Turn ON the ignition, with the engine OFF.
</td><td rowspan="1" valign="bottom" align="center">Go to Step 15
</td><td rowspan="1" valign="bottom" align="center">Go to Step 11
</td></tr> <tr> <td rowspan="1" valign="middle" align="center">8
</td><td rowspan="1">Test the ignition positive voltage circuit of the stop lamp switch for an open or short to ground. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?
</td><td rowspan="1" valign="bottom" align="center">Go to Step 18
</td><td rowspan="1" valign="bottom" align="center">Go to Step 9
</td></tr> <tr> <td rowspan="1" valign="middle" align="center">9
</td><td rowspan="1">Test for an open or short to ground in the TCC brake switch/cruise control release signal circuit of the stop lamp switch. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?
</td><td rowspan="1" valign="bottom" align="center">Go to Step 18
</td><td rowspan="1" valign="bottom" align="center">Go to Step 14
</td></tr> <tr> <td rowspan="1" valign="middle" align="center">10
</td><td rowspan="1" valign="top" align="left">Test the stop lamp switch signal circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?
</td><td rowspan="1" valign="bottom" align="center">Go to Step 18
</td><td rowspan="1" valign="bottom" align="center">Go to Step 14
</td></tr> <tr> <td rowspan="1" valign="middle" align="center">11
</td><td rowspan="1">Test the battery positive voltage circuit of the stop lamp switch for an open or short to ground. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?
</td><td rowspan="1" valign="bottom" align="center">Go to Step 18
</td><td rowspan="1" valign="bottom" align="center">Go to Step 13
</td></tr> <tr> <td rowspan="1" valign="middle" align="center">12
</td><td rowspan="1">Test the TCC brake switch/cruise control release signal circuit of the stop lamp switch for a short to voltage. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?
</td><td rowspan="1" valign="bottom" align="center">Go to Step 18
</td><td rowspan="1" valign="bottom" align="center">Go to Step 16
</td></tr> <tr> <td rowspan="1" valign="middle" align="center">13
</td><td rowspan="1">Test the stop lamp switch signal circuit for an open or short to ground. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?
</td><td rowspan="1" valign="bottom" align="center">Go to Step 18
</td><td rowspan="1" valign="bottom" align="center">Go to Step 14
</td></tr> <tr> <td rowspan="1" valign="middle" align="center">14
</td><td rowspan="1" valign="top" align="left">Inspect for poor connections at the harness connector of the engine control module (ECM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .
Did you find and correct the condition?
</td><td rowspan="1" valign="bottom" align="center">Go to Step 18
</td><td rowspan="1" valign="bottom" align="center">Go to Step 16
</td></tr> <tr> <td rowspan="1" valign="middle" align="center">15
</td><td rowspan="1">Inspect for poor connections at the harness connector of the stop lamp switch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .
Did you find and correct the condition?
</td><td rowspan="1" valign="bottom" align="center">Go to Step 18
</td><td rowspan="1" valign="bottom" align="center">Go to Step 17
</td></tr> <tr> <td rowspan="1" valign="middle" align="center">16
</td><td rowspan="1">Replace the ECM. Refer to Control Module References .
Did you complete the replacement?
</td><td rowspan="1" valign="bottom" align="center">Go to Step 18
</td><td rowspan="1" valign="bottom" align="center">--
</td></tr> <tr> <td rowspan="1" valign="middle" align="center">17
</td><td rowspan="1">Replace the stop lamp switch. Refer to Stop Lamp Switch Replacement .
Did you complete the replacement?
</td><td rowspan="1" valign="bottom" align="center">Go to Step 18
</td><td rowspan="1" valign="bottom" align="center">--
</td></tr> <tr> <td rowspan="1" valign="middle" align="center">18
</td><td rowspan="1" valign="top" align="left">
- Use the scan tool in order to clear the DTCs .
- Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.
</td><td rowspan="1" valign="bottom" align="center">Go to Step 2
</td><td rowspan="1" valign="bottom" align="center">System OK
</td></tr></tbody></table>
thanks.
.
2wd.
.
looks like the print out from the dealership. I'm going to have to keep going down the list
.
2wd.
.
looks like the print out from the dealership. I'm going to have to keep going down the list
ok i'll keep researching... are you on the road (anywhere near 95 in ct) or at home? i've got a tech2 and can lend you a hand.
home until at least Tuesday. Wifes got me pretty tied up with the to do list for the weekend.
.
Thanks for the help and offer!
.
Thanks for the help and offer!
here's the lates update.
got in the truck to pull it out into the the sunshine. nice day today.
Elec brake showed it was hooked to a trailer.
checked the plug in the bed all looked good.
Disassembled the elec brake and found a bunch of corrision on the back of circuit board. cleaned that off and reassembled/installed. Doesnt think there is a trailer hooked until I plugged in to my trailer. But unhooked still throwing a short circuit code sometimes.
maybe time for a new elec trailer brake controller?
On one of the last trips I unplugged the brake control to try to rule it out. Drove from PA home, no cruise the entire time. But would the 40 key cycles with the code come into play on that trip?
edit - found a troubleshooting for this brake, the oc w/o a trailer means its ok. with a trailer means short. so guess it might be fine.
got in the truck to pull it out into the the sunshine. nice day today.
Elec brake showed it was hooked to a trailer.
checked the plug in the bed all looked good.
Disassembled the elec brake and found a bunch of corrision on the back of circuit board. cleaned that off and reassembled/installed. Doesnt think there is a trailer hooked until I plugged in to my trailer. But unhooked still throwing a short circuit code sometimes.
maybe time for a new elec trailer brake controller?
On one of the last trips I unplugged the brake control to try to rule it out. Drove from PA home, no cruise the entire time. But would the 40 key cycles with the code come into play on that trip?
edit - found a troubleshooting for this brake, the oc w/o a trailer means its ok. with a trailer means short. so guess it might be fine.
Last edited: