This has happened a few times in the last month. I get into the car and no stater spin. It acts like the clutch isn't depressed for start. Has pwr to everything, but goes dead like the ignition is cutting pwr to everything for a start. If I drop the battery and reattach sometimes it clears, sometime it takes awhile. I think this is a security issue, possibly with the ign not reading the key correctly? I have tried to narrow down when it happens, but it is so sporadic that I cant establish a pattern. Any ideas?

 

Bad solenoid, common problem.. too much heat from the right side exhaust . Get a starter solenoid if you can find one, or replace the whole starter/solenoid

 

Pull your codes.

http://www.c5forum.com/ayc/dtcdic.php

 

It could be a number of things, clutch switch, dirty contacts on key, key switch, theft deterrent relay, and possible bad power connections on starter, also check your negative battery connections to chassis. Problem will have to get worse before you can really find out what is causing your no start sometimes.

 

98.645% That it's your solenoid! If its the solenoid, it will NOT throw a DTC. It just wont crank. If you whack the solenoid while someone holds the key to start, it will crank if its the solenoid. I got mine from a starter alternator rebuild place for around $50.

Solved my NO CRANK ISSUE.

Ive been told that a F body solenoid will fit BUT, you have to get the push on terminal and solder it on to your purple solenoid crank wire. AutoZone has them.

BC

 

To test the solenoid. I put a circuit test light on the small terminal on the solenoid. It doesn't appear to be getting any pwr to the solenoid when I hit the key. Should it not have voltage?

Pulled some troubling codes.

BCM 2723 H Pass Key detection Circuit????

BO RFA U1096 loss of communication with IPC
1064 loss of communication with BCM
1016 loss of communication with PCM
2120 Accelerator Pedal Position (APP) Sensor 1 Circuit

 

It's more than likely that BCM 2723 due to the key pellet being dirty or not getting good contact

Clean the key off real good with electrical/contact cleaner and a pencil eraser on the pellet itself.

Try and work some of the cleaner on the key into the lock cylinder.

The cylinder itself can go bad over time and cause this issue too but first I'd try cleaning the key

 

Sounds like it's leaning toward a class 2 issue(or ignition switch). You must resolve communication with the BCM/PCM, before you can do anything else......period.

 

what lucky says is correct too( as usual) the ignition switch itself...the contacts inside can get dirty and need to be cleaned off with fine grit sandpaper or something if you don't want to replace.

there is a write up here: http://forums.corvetteforum.com/c5-t...errerid=228945

this will basically explain how to change your lock cylinder also if that seems to be the issue. I'll say this though...if your key seems nice and snug/tight in the ignition and you've never had a hard time actually getting it to turn...the lock cylinder itself is more than likely fine.

I would clean the contacts on the ignition switch and get a new pellet put in the key. It's cheap and will prolly take care of the codes.

 

Same thing has happened to me a few times ... and is seems it ONLY does it after the car has sat stored over the winter time. Battery is always on the battery tender in my case. I have not got around to trying to find out what's the root cause yet. My 'Security' light was also on after starting, so have to believe it's something with the security system. See details here:

http://forums.corvetteforum.com/c5-t...questions.html

 

Thanks for the ideas and links guys. I will try to eliminate some of the possible culprits and see what I get. Can I bypass the theft deterrent relay to take that out of the equation? Right now I wish some one would steal it...

 

No, but you can bypass the VATS using a resistor. If you have "no communication" with the BCM and PCM when you check your codes......that MUST be resolved first.

 

Next time it does it smack the starter with a hammer if it starts it for sure the solenoid.

 

OK power to mini fuse 14 when I hit the key. Should I not have 12 volts then at the clutch switch? http://farm5.static.flickr.com/4135/...e157e441_b.jpg I have no power at the clutch switch. When I jump 12volts from the fuse #14 to the yellow wire on the clutch switch she fires right up. So it appears that the pwr is being lost from the fuse to the switch. What is the routing of that wire? It is a wiring jungle under the dash.

 

Are you saying you do not have 12 volts to pin A into the clutch switch, or no 12 volts out of the clutch switch (pin B), when the clutch is depressed?

 

No pwr to the clutch switch. If I jump pwr from fuse 14 to the out side (yellow wire) of the clutch switch it fires right up. Now I have to track the pwr from fuse 14 to the in side of the clutch switch. It is going to be a nightmare to track the wire.

 

If nothing has been done to the car, the chances of the wire being broken between the load side of fuse #14, and the clutch switch, are remote at best. Sorry for asking, but you are sure the fuse is good? Also, how does the fuse socket contacts look? What is the resistance of the load side of fuse #14 and pin A on the clutch switch? Did you check the resistance across the switch (pin A and B) with the clutch pedal depressed?

 

Problem found. Wire broke inside of bundle under dash. Must have been damaged when replacing steering sensor, and finally gave way. I should have thought about that, in fact I inspected all the wires and they looked good. It was buried in the wrapped bundle. Thanks for all the suggestions and links. I would have never found it without them.

In summary the start circuit . Power passes from the ign in crank mode to switch through fuse 14 then to the clutch position switch (Purple wire). When the switch is made the "out side" ( yellow wire) goes to the TDR relay above the BCM. The TDR has a always hot red, a purple to the Starter, the yellow from the clutch switch, and a yellow/black wire from the BCM. This yellow/black wire is grounded by the BCM when the resistance from the key VAT pellet is the correct value, allowing the relay to close then allowing a start. If your key VAT pellet was bad, can the car be started by grounding the yellow and black wire, taking the BCM out of the loop? Would this cause any Damage to the BCM?

Thanks Again for the help

 

This damn thing is driving me nuts. Still starts when it feels like it. I have tested everything including the TDR. It will only start when I ground the TDR, taking the BCM out of the loop. Can this still be an issue with the key pellet? What is involved with swapping out the BCM?
What would happen if I would hard wire a ground to the TDR's ground wire? Here are some codes RFA U1096,U1064,U1016. BCM C1255. 1001, 2723

 

This is your problem!! Figure out why your resistor pellet on the key isnt reading all the time!!

DTC B2723
Circuit Description


The body control module (BCM) supplies a 5 volt signal and a ground circuit for the PASS-Key® system. This allows the BCM to detect PASS-Key® resistance values. Inserting the PASS-Key® (with resistor pellet) in the ignition lock cylinder completes the PASS-Key® circuit. Contacts in the ignition lock cylinder mate with the pellet contacts. The BCM compares the resistance value of the key pellet to the valid resistance programmed into the BCM. If the proper resistance value is read, the BCM allows the following functions to occur:

The theft deterrent relay to energize.
The steering column to unlock.
The BCM sends a message through the serial data line to the powertrain control module (PCM) to allow fuel delivery to occur.
If the resistance value is incorrect, a malfunction is present and a DTC will set.

Conditions for Setting the DTC
The voltage level sampled at the BCMs PASS-Key® signal circuit is incorrect, signaling that an invalid PASS-Key® resistance was detected, and a short or an open is present.
This condition must be present for 1 second.
Action Taken When the DTC Sets
The BCM stores DTC B2723 in memory.
The BCM sends a message to the instrument cluster to illuminate the SECURITY indicator.
The BCM disables the theft deterrent relay.
The PCM will not allow fuel delivery to occur.
The BCM disables sampling of the PASS-Key® resistance for a time-out period of 3 minutes.
The steering column remains in the locked position.
Conditions for Clearing the DTC
This DTC requires an ignition cycle in order to change from current to history.
The BCM detects a valid PASS-Key® resistance value on the PASS-Key® signal circuit.
A history DTC will clear after 50 consecutive ignition cycles if the condition for the malfunction is no longer present.
Use the instrument panel cluster (IPC) clearing DTCs feature.
Use a scan tool.
Diagnostic Aids
If the key resistor pellet is incorrect, there will be no BCM outputs to the theft deterrent relay or to the PCM. This state will last about 3 minutes. If a key is inserted, or the ignition is turned ON again before the 3 minute time frame is complete, the timer will reset to 3 minutes. Disconnecting the battery will not clear the timer sequence, but the timer will reset to 3 minutes when the battery power is restored. Even if a proper key is inserted during one of the time periods, the vehicle will not start until the total time period has elapsed.
If there is a short between the PASS-Key® signal and ground circuit, or a short to ground on the PASS-Key® signal circuit, the vehicle will exhibit a no crank condition.
Test Description
The number below refers to the step number on the diagnostic table.

This test verifies the integrity of the key resistor circuits between the ignition switch and the BCM.

Step
Action
Yes
No

Schematic Reference: Theft Deterrent System Schematics

Connector End View Reference: Theft Deterrent System Connector End Views

1
Did you perform the Theft Deterrent Diagnostic System Check?
Go to Step 2
Go to Diagnostic System Check - Theft Deterrent

2
Install a scan tool.
Turn ON the ignition with the ignition OFF.
Select the BCM Display DTCs function on the scan tool.
Does the scan tool display B2723 as a current DTC?
Go to Step 3
Go to Testing for Intermittent and Poor Connections in Wiring Systems

3
Inspect the ignition key for dirt or obvious damage.

Does the ignition key appear dirty or damaged?
Go to Step 8
Go to Step 4

4
Turn OFF the ignition.
Disconnect the ignition lock cylinder connector.
Connect a J 35628-A Vats/Passkey Interrogator using terminal adapters from a J 35616-A to the key resistor input circuit and key resistor reference ground circuit.
Insert the ignition key into the key code reader on the J 35628-A and note the code on the LCD display.
Turn the rotary switch on the J 35628-A to the same code number as the ignition key.
Attempt to start the vehicle.
Does the vehicle start?
Go to Step 7
Go to Step 5

5
Test the following circuits for an open or a short to voltage:

The key resistor input circuit
The key resistor reference ground circuit
Did you find and correct the condition?
Go to Step 11
Go to Step 6

6
Inspect for poor connections at the harness connector of the BCM. Refer to Testing for Intermittent and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?
Go to Step 11
Go to Step 10

7
Inspect for poor connections at the harness connector of the ignition lock cylinder. Refer to Testing for Intermittent and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?
Go to Step 11
Go to Step 9

8
Clean or replace the ignition key as necessary. Refer to Replacing Keys .

Did you complete the procedure?
Go to Step 11
--

9
Replace the ignition switch lock cylinder. Refer to Ignition Switch Lock Cylinder Replacement in Instrument Panel, Gages and Console.

Did you complete the replacement?
Go to Step 11
--

10

Important
When replacing the BCM, perform the relearn procedure. Refer to Body Control Module (BCM) Programming/RPO Configuration in Body Control System.


Replace the BCM. Refer to Body Control Module Replacement in Body Control System.

Did you complete the repair?
Go to Step 11
--

11
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.
Does the DTC reset?
Go to Step 2
System OK



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You can fix this later!!

1255

DTC C1255 or C1256
Circuit Description
This DTC identifies a malfunction within the electronic brake control module (EBCM).

Conditions for Running the DTC
The ABS conditions and the braking conditions are normal.

Conditions for Setting the DTC
An internal EBCM malfunction exists.

Action Taken When the DTC Sets
C1255
If equipped, the following actions occur:

The EBCM disables the DRP/ABS/TCS/VSES for the duration of the ignition cycle.
The ABS indicator turns ON.
The Traction Control and Active Handling indicator turns ON.
The red Brake warning indicator turns ON.
The DIC displays the following messages:
Service ABS
Service Traction System
Service Active Handling
The EBCM will also set DTC C1248.
For some DTC C1255xx, the EBCM disables the variable effort steering (VES) for the duration of the ignition cycle.
C1256
The ABS remains functional.
The ABS indicator remains OFF.
Conditions for Clearing the DTC
The condition for the DTC is no longer present and the DTC is cleared with a scan tool.
The EBCM automatically clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles.
Diagnostic Aids
The scan tool displays 2 additional characters after the DTC. Take note of the 2 character code and any other DTCs that are set. The 2 character code is an engineering aid used in order to determine the cause of the internal malfunction.
When the scan tool displays DTC C1255m3, the EBCM has not been programmed. Perform the setup procedure for the EBCM.
Test Description
The number below refers to the step number on the diagnostic table.

Determines whether the DTC is current.

Step
Action
Yes
No

Schematic Reference: ABS Schematics

1
Did you perform the ABS Diagnostic System Check?
Go to Step 2
Go to Diagnostic System Check - ABS

2
Install a scan tool.
Turn ON the ignition, with the engine OFF.
Use the scan tool in order to clear the DTCs.
With the scan tool, perform the Automated Test.
Does the DTC reset as a current DTC?
Go to Step 3
Go to Testing for Intermittent and Poor Connections in Wiring Systems

3
Replace the EBCM. Refer to Electronic Brake Control Module (EBCM) Replacement .

Did you complete the repair?
Go to Step 4
--

4
Use the scan tool in order to clear the DTCs.
With the scan tool, perform the Automated Test.
Does the DTC reset?
Go to Step 2
System OK



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