C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

What does the jamb switch actually do?

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Old Jul 27, 2022 | 07:53 PM
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Default What does the jamb switch actually do?

On my '90.

just replaced the door switches again, because my interior lights were acting up and killing my battery again.

That seems to be worked out, now.

But...I noticed that the ''door ajar'' light on the dash doesn't work when the driver side door is open. Though it does work when th passenger door is open. But only when the key is in the ignition.

From the diagram in the FSM, I see another switch (#45 on the diagram) labeled ''jamb switch.''

Would that be the likely reason why the ''door ajar'' light display does not display on the dash whe nthe driver side door is open?

Also, my door switches for the hatch release don't work.

It seems logical to me that the reason they don't work is maybe because the car thinks the door is actually closed, even though it's open?

The hatch release works on the center console button.

Thanks for any insight.



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Old Jul 27, 2022 | 08:19 PM
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Originally Posted by Natty C
From the diagram in the FSM, I see another switch (#45 on the diagram) labeled ''jamb switch.''

Would that be the likely reason why the ''door ajar'' light display does not display on the dash whe nthe driver side door is open?

Also, my door switches for the hatch release don't work.

It seems logical to me that the reason they don't work is maybe because the car thinks the door is actually closed, even though it's open?

The hatch release works on the center console button.
Yeah...two switches. One in the jamb...the other at the rear of the door. Right now, I can't remember which switch does what. Probably the lights for one and the display warning for the other. Push each door switch when your passenger door is open to determine what each does....lights or door ajar. Then you'll know which switch to service on the DS.

You're not thinking on the door hatch release. The door has to be open to press it! If they're like my 89 switches, they have sliding contacts. Probably need to be cleaned. The one in the glove box won't work when the car is in drive or running -- which ever. (Can't remember the exact connection w/o looking at schematic. Could be different for stick vs auto?)


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Old Jul 27, 2022 | 09:02 PM
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Originally Posted by GREGGPENN
Yeah...two switches. One in the jamb...the other at the rear of the door. Right now, I can't remember which switch does what. Probably the lights for one and the display warning for the other. Push each door switch when your passenger door is open to determine what each does....lights or door ajar. Then you'll know which switch to service on the DS.

You're not thinking on the door hatch release. The door has to be open to press it! If they're like my 89 switches, they have sliding contacts. Probably need to be cleaned. The one in the glove box won't work when the car is in drive or running -- which ever. (Can't remember the exact connection w/o looking at schematic. Could be different for stick vs auto?)
Well I definitely know that the outer door switches work the lights.

But they're also properly labeled ''ajar indicator switch'' in the FSM. So that makes me think that they have something to do wit hthe ''door ajar'' light on the dash.

So far I've tracked the ''jamb switch'' down to the key warning chime and nothing else so far.

I did read some place on the forum about autos and manuals being different as far as the console hatch swith goes.

Reading through the CCM functions section of the FSM now.

Last edited by Natty C; Jul 27, 2022 at 09:14 PM.
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Old Jul 27, 2022 | 09:26 PM
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CCM FUNCTIONS

The Central Control Module (CCM) performs the following functions:


Ambient Light Signal Processing

Chime (Belts/Lights/Key Warning) Control Courtesy Lamp Control

Dimming Control

Instrument Cluster LCD Backlighting Instrument Cluster Gages Backlighting LCD Backlighting (Radio, HVAC)

LED Indicator Dimming

High-Beam Indicator Dimming Driver Information Center (DIC) Switches

Trip Odometer Reset

Average Fuel Economy Reset

Display InstantlAverage Fuel Economy Display Fuel Range

Display Normal/Trip Odometer English/Metric Mode Selection On-Board Diagnostics Control

Engine Oil Life Monitor Reset

Fuel Level Detection/Processing Instrument Panel LCD Digit Display

Fuel Level

Vehicle Speed

Trip Odometer

Normal Odometer Fuel Range

Instant Fuel Economy Average Fuel Economy

Rear Defog Control

Normal Odometer Processing Status Warnings

Battery OvervoltagelUndervoltage Engine Coolant Overtemperature Engine Oil Overtemperature

Fuel Level Low

System Component Fault Detection System Diagnostics Processor/Controller Trip Computer Processing For:

Instantaneous Fuel Economy Average Fuel Economy

Fuel Range

Trip Odometer

UART Serial Communications Master Universal Theft Deterrent (UTD) Control Vehicle Speed DetectionlProcessing Vehicle Anti-Theft System (VATS)



WAKE-UPS

are signals that will turn the CCM ~ON and cause it to begin active control and/or

monitoring.


The Wake-Ups are as follows:

​​​
  • Key In Door Lock Switch; L & R
  • Door Ajar Switch; L & R
  • Power Door LockiUnlock Switch; L & R
  • Hatch Ajar Switch
  • Key In Ignition Switch
  • Ignition ON (IGN 3)
  • Park lamps ON

    After the CCM is awake and the wake-up input is removed (i.e., a door is opened, then closed) the CCM will go to sleep" again in 5-15 seconds. An exception to this is if the CCM sees engine RPM while it is awake (as it would under normal operating conditions). In this instance, the CCM will stay awake for up to 21 minutes, after the ignition is turned OFF and all wake-ups are removed.
If the CCM sees a Door Ajar wake-up, and that wake-up remains active (i.e., the door remains open) for 15 minutes, the CCM will turn courtesy lights will OFF if they were ON.

This is done to prevent battery drain if a door is inadvertently left open for an extended period of time. If the CCM sees the Hatch Ajar wake-up, and the wake-up remains active, indicating the hatch is still open, after 10 minutes the CCM will go to sleep, but the cargo area lamps will stay ~~ON" until the hatch is closed.

If the ignition key is in the ignition switch, but the switch is not in the START or RUN position, the CCM will stay awake for 30 minutes.
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Old Jul 28, 2022 | 11:14 PM
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I dunno. Guess I'm gonna have to do it the old fashioned way and go probing all of the electrical stuff.

It's probably a short some place, if it's just not the door ajar light on the I/P for the driver side door.

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