lefrog

My 02 C5Z race car is almost stripped of everything but I still have the stock ignition key (and I have only one) and it is only a matter of time before this thing fails and I get stranded on race weekend not being able to get the car started.

Is there an easy way to rewire an ignition switch and a push start button and get rid of the whole key + tumbler stuff while keeping the stock ECU.
Is it just a matter of putting the same resistor as in the key, or is there more to it?

FAUEE

On older cars, it's just a resistor. Depending what version of Passkey you have, you might be able to get by it with a resistor or you may need a relay and resistor setup.

I'd look into what it would take to do a remote start on the car. You're doing essentially the same thing with your push button start.

I've been looking at one of the cheapo proximity key/push start units on ebay for my C4 and DD, I've been spoiled by smart keys now. They do basically the same thing except add an RFID keyfob so the car unlocks when you get near and will only allow you to start it when the key is near. If your car is totally stripped out, this may or may not be a security issue for you. That's probably the last bit of anti-theft device left on the car. Just something to think about.

lefrog

Good pointer, thanks. I don't really care about security, the doors don't have locks or windows anymore! Will look into some remote starter solution and try to implement something similar.

trackboss

If you are not restricted by budget, knowledge, or rules you should consider re-wiring the car and doing a stand alone efi (fast, etc.). Years ago I went through a stock harness and removed all unnecessary wires, pins, etc. Basically made a race only harness using factory connectors, computer, etc. It was very labor intensive and I was still tied to the stock computer. If I did it again I would custom wire it my way and use a stand alone efi. Much more user friendly. There is the added bonus that one will know exactly where everything is and can service it if necessary without going blind looking through factory wiring diagrams.

LateBreak

If you plan to keep your BCM and stock PCM I'd keep the original ignition switch and just bypass the key resistor. Removing the BCM and making the PCM standalone would allow you to do a simple push-button setup but also render your stock gauges and other conveniences useless.

If you're so inclined to delete the tumbler while keeping the BCM, I'd start with a wiring diagram to see what happens at each stage of turning the key. Once you've decided how to wire it, I'd make a dummy harness that plugs into the original plug so that you can test functionality before cutting any wires.

On my car, I've kept the original tumbler for simplicity, but there's a security hiccup if I turn the battery cutoff switch on while the key is in the ignition. The car will start, but kills if you try moving, the fix is to pull the key and restart with the switch on. It's annoying but I haven't found a way to defeat it yet so we live with it.

geerookie

Not True. BCM has no affect on your stock gauges. I've had mine out for years and still use the stock gauges.

Push button start is pretty easy. Bypass all the factory wiring.
Run a primary cable to the starter and then wire the push button just like you would an old 60's key switch to the solenoid wire on the starter.
Make sure it supplies power to the solenoid when in the start position.

LateBreak

I'll be damned, I stand corrected. Did you lose any other functionality when you ditched the bcm?

geerookie

Only what the BCM controlled.
The following components provide direct input to the BCM. Other systems can use this input information in order to carry out various functions:
BCM Inputs •Ambient Light Signal Processing -- provides the BCM with the ambient light input information for interior lamp illumination and automatic headlamp operation.
•Column Feedback Switch -- provides steering column feedback information to the BCM in order to determine if the steering column was successfully locked or unlocked.
•Door Ajar Switches -- provides door ajar status to the BCM.
•Fog Lamp Switch, Front -- provides fog lamp switch activation input to the BCM in order to turn the front fog lamps ON or OFF.
•Fog Lamp Switch, Rear (export)-- provides fog lamp switch activation input to the BCM in order to turn the rear fog lamps ON or OFF.
•Folding Top Ajar Switch--provides folding top ajar status to the BCM.
•Folding Top Release Switch -- provides folding top release switch information to the BCM.
•Hatch Ajar Switch -- provides hatch ajar status to the BCM.
•Hatch Release Switch -- provides hatch release switch information to the BCM.
•Headlamps OFF -- provides the BCM with headlamps ON or OFF status for automatic headlamp operation.
•Hood Ajar Switch (export)-- provides hood ajar status to the BCM.
•Ignition Switch -- provides the BCM with ignition position status.
•Key In/Out Ignition Switch -- allows the BCM to detect when a key is IN or OUT of the ignition.
•Monitored Loads -- monitors electrical loads left ON after the ignition switch is turned OFF.
•Pass-Key® Resistance -- determines the resistance of the key pallet for the PASS-Key® system.
•Rear Defogger Switch -- provides rear defogger switch activation input to the BCM in order to turn the rear defogger ON or OFF.
•Turn Signal Monitor, LH/RH -- monitors the turn signal status for the DRL.
•Traction Control System (TCS) Switch -- provides traction control switch activation input to the BCM in order to turn the TCS ON or OFF.

The BCM directly controls the following outputs. Other systems may request the BCM to control these outputs for various functions:
BCM Outputs •Automatic Headlamp/Parklamp Control -- provides output control to turn ON the headlamps and parklamps when it's dark outside.
•Backup Lamp Relay -- provides output control in order to energize the backup lamp relay for UTD and Approach Lighting functions.
•Console Lamp Dimming Control -- controls the console lamp illumination when the headlamps or the parklamps are ON.
•Courtesy Lamp Relay -- provides output control in order to energize the courtesy lamp relay when the courtesy lamp switch is ON.
•DRL Relay, LH -- when energized, the relay allows the BCM to use the LH front turn signals for DRL, Approach Lighting, and UTD functions.
•DRL Relay, RH -- when energized, the relay allows the BCM to use the RH front turn signals for DRL, Approach Lighting, and UTD functions.
•Fog Lamp Relay, Front -- provides output control in order to energize the front fog lamp relay when the fog lamp switch is ON.
•Fog Lamp Relay, Rear (export)-- provides output control in order to energize the rear fog lamp relay when the fog lamp switch is ON, or for Approach Lighting and UTD functions.
•Folding Top Release Relay--provides output control in order to energize the folding top relay when the folding top switch is pressed.
•Hatch Release Relay--provides output control in order to energize the hatch release relay when the hatch release switch is pressed.
•Horn Relay -- allows the BCM to energize the horn relay for UTD and RFA system functions.
•HVAC Lamp Dimming Control -- controls the HVAC lamp illumination when the headlamps or the parklamps are ON.
•Monitored Load Relay -- provides output control for the monitored load relay, allowing the BCM to shut off certain electrical loads in order to prevent battery rundown.
•PRNDL Lamp Control -- controls the PRNDL lamp illumination when the headlamps or the parklamps are ON (A/T only).
•Rear Defogger Relay -- provides output control in order to energize the rear defogger relay when the rear defogger switch is pressed.
•Steering Column Lock/Unlock Control -- provides output to control drive A and drive B for steering column lock/unlock operation.
•Steering Column Lock Relay -- allows the BCM to disable steering column lock functions.
•Theft Deterrent Relay -- allows the BCM to energize the theft deterrent relay for UTD functions.

lefrog

I need to look at the wiring diagram. It's the key detection mechanism that worries me and how I should wire it if I need to simulate that the key is inserted/removed (like the 'Remove key and wait 10 seconds' message that pops up every so often if you use the kill switch).
It looks like the issue you mention about the car killing if you try moving it is related to the column lock issue that cuts off fuel at 2mph if the computer thinks that the column is still locked. I sent my ECU to ECS to have it reprogrammed and get rid of that (among other things!).

I'll keep you posted with my progress when I figure things out!

Hi Volts Z06

I have a few comments and questions on this issue as well. I've done as Greg suggests and ran a push button to the starter. That works no problem. Because I had a pretty bad fire, we replaced my PCM wiring harness with a Painless one. That requires disabling the security feature through the PCM (which we did) so basically my ignition toggle switch powers the PCM, but I haven't been able to eliminate the key. While I agree the BCM doesn't control gauges (these are directly from the primitive CAN bus in the C5), it seems that I can hear a relay pulling in within the BCM when I keep the key in the circuit. I'm thinking the 2002 models have an additional layer of security which needs to be jumped out. Any thoughts and if so....I'm all for eliminating the BCM since it really isn't doing anything but this function anymore.

RX-Ben

If you delete the BCM you do not need to worry about the "remove key" message.

lefrog

If the BCM controls the TCS switch, how do I deactivate traction control or put it in competitive mode?

RX-Ben

One way is to cut the Tq Requested or Tq Delivered communication to the EBCM. You can also cut the light blue brake signal wire (#6 below). Both will default the system to AH/TCS off and ABS on.

Here is a link to the plug and the wiring. Ignore the notes.
https://docs.google.com/document/d/1...it?usp=sharing





Pin Wire Color Circuit No. Function [CONFIRM WITH GM SCHEMATIC]
A RED 1642 Battery Positive Voltage
B BRN 641 Ignition 3 voltage
C GRY 1787 Variable Effort Steering Actuator High Effort Control
D WHT 345 Variable Effort Steering Actuator Low Effort Control
E -- -- Not Used
F BLK/WHT 1251 Ground
G BLK 1250 Ground
1 -- -- Not Used
2 TAN/BLK 464 Delivered Torque Signal
3 LT GRN 1763 Steering Wheel Position Signal A
4 -- -- Not Used
5 LT GRN/BLK 1338 Lateral Accelerometer Input (JL4)
6 LT BLU 20 Stop lamp Supply Voltage
7 -- -- Not Used
8 RED 885 Left Rear Wheel Speed Sensor Low Reference
9 BRN 882 Right Rear Wheel Speed Sensor Signal
10 DK GRN 872 Right Front Wheel Speed Sensor Signal
11 LT BLU 830 Left Front Wheel Speed Sensor Signal
12 ORN/BLK 463 Requested Torque Signal
13 ORN/BLK 556 Low Reference
14-16 -- -- Not Used
17 BLK 2626 Brake Pressure Sensor Signal (JL4)
18 LT BLU 1764 Steering Wheel Position Signal B
19 DK BLU 716 Yaw Rate Sensor Signal (JL4)
20 -- -- Not Used
21 LT BLU 1122 ABS/TCS Class 2 Serial Data
22 BLK 884 Left Rear Wheel Speed Sensor Signal
23 WHT 883 Right Rear Wheel Speed Sensor Low Reference
24 TAN 833 Right Front Wheel Speed Sensor Low Reference
25 YEL 873 Left Front Wheel Speed Sensor Low Reference
26 -- -- Not Used
27 GRY 1056 Steering Wheel Position Sensor 5V Reference Voltage
28 LT BLU 2627 Steering Position Sensor Signal [TEST THIS SCHEMATIC – USE INSTEAD OF THE PAIR?]
29 -- -- Not Used

mdiiulio

Cheap and easy DIY for a new key, if you decide to just go that route.

Click Here

FuriousDonuts

Interesting, seems like the cleanest option for a track-only race car is BCM delete and directly wire to the starter.

Lefrog's fears are warranted. I had to miss a day when I fried my BCM during a rain race. Car wouldn't start- guessing because it couldn't pass the theft deterrent logic. Cost me enough points to put me out of winning the season championship.

[QUOTE="RX-Ben;1588638296"]One way is to cut the Tq Requested or Tq Delivered communication to the EBCM. You can also cut the light blue brake signal wire (#6 below). Both will default the system to AH/TCS off and ABS on. Here is a link to the plug and the wiring. Ignore the notes. [URL="https://docs.google.com/document/d/BLK/ .... [/QUOTE]

Since this keeps ABS on, would it also allow dynamic rear proportioning?

RX-Ben

ABS (as opposed to AH/TCS) still works as normal w/o the BCM. DRP is part of ABS, so it remains intact.