Shocks Inoperative Error Message

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Dec 29, 2011 | 03:48 AM

DeeGee

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From: Horncastle Lincolnshire, England

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Shocks Inoperative Error Message

I have an intermittent problem with the F45 shocks. I've posted before but never had a definitive reply.

Occasionally when I start the car I get a "shocks inoperative" message on the DIC. I know what the system does and, reading the description of how it processes error messages, the code is not remaining current:

"As long as the DTC is current, the message will be displayed after every ignition cycle"

The F45 system, as we all know, is useless and I really don't feel any difference when I'm driving. If it's failing safe to Sport mode, as the description suggests, it's impossible to tell.

There are no RTD codes but, again, from the description, it makes sense that a brief glitch wouldn't register as the DTC would be stored in the ESC module.

Anyone know why this occurs. My only thought is that its a bad/dirty connection at the shock?

Any other thoughts?

Real Time Damping Operation

The RTD system uses the information from other systems in order to execute certain functions.

The RTD system does not have a malfunction indicator lamp, but instead uses the Instrument Panel Cluster (IPC) for the display functions. When the RTD system detects a malfunction that sets a DTC, the RTD system sends a message on the serial data line directly or through the PCM to the IPC, which will display one of the following messages:

SHOCKS INOPERATIVE
SERVICE RIDE CONTROL
MAXIMUM SPEED

The SHOCKS INOPERATIVE message will only be displayed if the RTD system detects a malfunction that sets a DTC and causes the RTD system to disable all four shock absorbers. The RTD system will send a message on the serial data line to the IPC to display this message.

The SERVICE RIDE CONTROL message will only be displayed if the RTD system detects any malfunction that sets a DTC. The RTD system will send a message on the serial data line to the IPC to display this message.

The MAXIMUM SPEED message will only be displayed if the RTD system detects a malfunction that sets a DTC and causes the RTD system to disable all four shock absorbers. The RTD system will send a message on the serial data line to the PCM indicating that all four shock absorbers were disabled. The PCM then sends a message to the IPC to display this message.

The ESC module has the ability to store Diagnostic Trouble Codes (DTCs) as current or history codes. Most RTD system malfunctions will display a message in the IPC and set a DTC. The message will remain ON until the RESET button is pressed on the Driver Information Center (DIC). As long as the DTC is current, the message will be displayed after every ignition cycle and the RESET button must be pressed to bypass the message.

The RTD system uses an ignition cycling diagnostic approach in order to reduce the occurrence of false or intermittent DTCs that do not affect the functionality of the RTD system. This allows for the fail-soft actions to be taken whenever a malfunction condition is current, but requires the malfunction to be current for a certain number of ignition cycles before the corresponding malfunction code and message will be stored or displayed.

If the RTD detects a malfunction, the RTD system defaults with a fail-soft action. A fail-soft action refers to any specific action the RTD system takes in order to compensate for a detected malfunction. A typical RTD fail-soft action would be if the RTD system detects a malfunction with the ride control switch, the RTD system will ignore this input and fail-soft to the SPORT ride setting.

Last edited by DeeGee; Dec 29, 2011 at 04:05 AM.

Dec 29, 2011 | 04:04 AM

DeeGee

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From: Horncastle Lincolnshire, England

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I don't have codes in the RTD section but I have a PCM code that is related - P1652H.

Not sure if that's relevant as my fault is on start not when driving.

DTC P1652
Circuit Description

The PCM controls the Powertrain Induced Chassis Pitch by grounding the control circuit via an internal switch called a driver. The primary function of the driver is to supply the ground for the controlled component. The driver has a fault line which is monitored by the PCM. When the PCM commands a component ON, the voltage of the control circuit should be low, near 0 volts. When the PCM commands the control circuit to a component OFF, the voltage potential should be a high 5 volts (+/- 0.5 volts). If the fault detection circuit senses a voltage other than what the system expects, the fault line status changes causing the DTC to set.

The PCM receives an 5 volt (+/- 0.5 volt) reference signal from the electronic suspension control (ESC) module on the Powertrain Induced Chassis Pitch circuit. The PCM grounds this circuit when the vehicle accelerates rapidly or brakes hard. When the chassis pitch input circuit goes low to about 0 volts, the ESC module commands all four shock absorber solenoids to a firm position. The PCM calculates the chassis pitch information based on the engine torque and the vehicle braking force.

Last edited by DeeGee; Dec 29, 2011 at 04:06 AM.

Dec 29, 2011 | 04:57 PM

DeeGee

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From: Horncastle Lincolnshire, England

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bump

Don't say I found a question that no one can answer?

Dec 29, 2011 | 05:07 PM

Paul Wood

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From: San Antonio Texas

DeeGee I wish I could help as you are always so good about answering everyone else's problems but I just don't have the technical knowledge. Sorry!
Where is Lucky? He always has answers to electrical issues! Good Luck to a great Corvette Forum member!

Dec 30, 2011 | 03:13 AM

DeeGee

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From: Horncastle Lincolnshire, England

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Quote:

Originally Posted by Paul Wood

Thanks for the sympathy Paul

How come I get the problems that no one else has seen

Dec 30, 2011 | 12:29 PM

Bill Curlee

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From: Anthony TX

CI 6,7,8,9,11 Vet

St. Jude Donor '08

Have you attempted to read the DTC during that ignition cycle while the car is on and the message is active?? Sometimes turning the ignition OFF and back on will clear EBTCM and RTD DTCs.

Im sure that you have seen my opinions on that suspension system

Buy your self a late CHRISTMAS PRESENT and install some C6 ZO6 shocks, a ZO6 or Z51 sway bar OR get the C6 package that Gene Culley has. The RTD de-install is PAINLESS!

You will need a crow bar to break the grin off your face after the first drive!

If there really are not any RTD DTCs,, you will need to break out the volt meter and see if that signal is there and if its failing.

Take a look at the ESC Module and connectors back in the trunk well. The past two people that I have helped fix their RTD issues, BOTH had water /moisture damaged modules.

Give that a try.

Bill

Dec 31, 2011 | 03:03 AM

DeeGee

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From: Horncastle Lincolnshire, England

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Thanks Bill

I've checked the codes virtually every time it's happened. Definitely no codes in Section 3, just the PCM code in Section 1. It only occurs on start up and the DIC message clears almost straight away without having to hit reset which makes me think it's transitory.

I'll check the ESC module as thats something I haven't done. The car's a weekend car now and it's garaged overnight. I live in England so it definitely gets wet but I don't normally suffer from corroded parts. Certainly worth a look though.

As you say, there was a good reason that the F55 was introduced