Key Fob schematic
Thread Starter
Instructor
Joined: Sep 2015
Posts: 164
Likes: 18
From: Fort Wayne IN
Key Fob schematic
My 1994 Key Fob stopped working. A key fob tester shows no signal coming from the fob. Battery is good, all solder joints inside look good. Not much in there except for an IC and what looks like a crystal, or is it a movement sensor? If it's a crystal, does anyone know if it can be replaced from another fob? New fobs are about $200, Does anyone have a schematic for the fob or a generic part number for the IC?
Last edited by Scooter94; Sep 23, 2019 at 02:10 AM.
Safety Car
Joined: Apr 2016
Posts: 4,648
Likes: 1,059
From: N.E. Ohio OH
Finalist 2020 C4 of the Year - Modified
if you want to get it repaired, so say and I will PM you the lady's name and email address. this is the response I got:
I do repair them as a hobby now. Yes, I designed the new style C4 93-96 replacement fob for GM, the one currently sold at dealerships. The old style fob is a snap fit with a latch that always breaks etc....
Cost depends on what's wrong and which fob, new or old style.
For either fob I charge a minimal fee to do diagnostics which is $25 plus priority return shipping in a box for $8....that's a minimum. Overall average minor repair total, including diagnostic base fee, of the internal core electronics can average around $40-45. The most expensive repair is a broken antenna winding. I of course charge for a new proper sized battery as well if needed. (Not all CR2450 are the same physical profile and diameter. ) After repair it gets full performance and function test and little mods to update. For example the current manufacture of my new style fob leaves off a specified felt pad on the inside top of the case for adding battery shock protection, so I always add that.
My payment methods are limited.
-Cash is fast
-USPS Postal money order purchased at a US post office. No other type of money order....no personal checks, and no PayPal.
-Sometimes I accept "fee free" egift cards for Amazon if someone just wants to use a credit card... ��
Cost depends on what's wrong and which fob, new or old style.
For either fob I charge a minimal fee to do diagnostics which is $25 plus priority return shipping in a box for $8....that's a minimum. Overall average minor repair total, including diagnostic base fee, of the internal core electronics can average around $40-45. The most expensive repair is a broken antenna winding. I of course charge for a new proper sized battery as well if needed. (Not all CR2450 are the same physical profile and diameter. ) After repair it gets full performance and function test and little mods to update. For example the current manufacture of my new style fob leaves off a specified felt pad on the inside top of the case for adding battery shock protection, so I always add that.
My payment methods are limited.
-Cash is fast
-USPS Postal money order purchased at a US post office. No other type of money order....no personal checks, and no PayPal.
-Sometimes I accept "fee free" egift cards for Amazon if someone just wants to use a credit card... ��
Heel & Toe
Joined: Aug 2018
Posts: 17
Likes: 3
From: Nebraska
I have had the lady mentioned above repair 2 FOBs and her work was great. I will repeat what she told me about FOBs, use only a Renata battery as Sony and others are too thick and will crush a capacitor or break the latch.
I think what the OP was asking about a movement sensor, if it is silver about 1/2" long and 1/8" thick, that's what it is. A small ball is enclosed in it which moves and wakes up the FOB.
A question to the OP, have you programmed the FOB from the car?
No need to use the buttons on the FOB if the FOB and car are talking to each other. The only time I use the button is to open the hatch.
I think what the OP was asking about a movement sensor, if it is silver about 1/2" long and 1/8" thick, that's what it is. A small ball is enclosed in it which moves and wakes up the FOB.
A question to the OP, have you programmed the FOB from the car?
No need to use the buttons on the FOB if the FOB and car are talking to each other. The only time I use the button is to open the hatch.
Last edited by S Roche; Sep 23, 2019 at 05:40 PM.
Thread Starter
Instructor
Joined: Sep 2015
Posts: 164
Likes: 18
From: Fort Wayne IN
I have had the lady mentioned above repair 2 FOBs and her work was great. I will repeat what she told me about FOBs, use only a Renata battery as Sony and others are too thick and will crush a capacitor or break the latch.
I think what the OP was asking about a movement sensor, if it is silver about 1/2" long and 1/8" thick, that's what it is. A small ball is enclosed in it which moves and wakes up the FOB.
A question to the OP, have you programmed the FOB from the car?
No need to use the buttons on the FOB if the FOB and car are talking to each other. The only time I use the button is to open the hatch.
I think what the OP was asking about a movement sensor, if it is silver about 1/2" long and 1/8" thick, that's what it is. A small ball is enclosed in it which moves and wakes up the FOB.
A question to the OP, have you programmed the FOB from the car?
No need to use the buttons on the FOB if the FOB and car are talking to each other. The only time I use the button is to open the hatch.
OK on the sensor. Figured that is what it was.
Le Mans Master
Joined: Jan 2006
Posts: 5,620
Likes: 206
From: Orlando FL
Make sure the battery checks 3.0 to 3.2 volts for reliable operation.
The key FOB testers in the part stores don’t work for the C4 Corvette FOBs. This is because they are a passive FOB where no button is pressed to open the doors.
Make sure the car is NOT in sleep mode. When you turn the key the PKE light should light for 2 seconds. If it does it is not in sleep mode. If it does not light, then either it is in sleep mode or the PKE module is bad.
I got to ask do you know how to operate you FOB and put it in and out of sleep mode?
Try to program you FOB. See if the car will go thru the proper steps with the PKE light indicating the proper signals. If the car won't go thru programming, then the PKE module may be bad because the FOB will not prevent the car from trying to program the FOB.
Having a spare FOB to try this would be the first best thing to try with the programming
The key FOB testers in the part stores don’t work for the C4 Corvette FOBs. This is because they are a passive FOB where no button is pressed to open the doors.
Make sure the car is NOT in sleep mode. When you turn the key the PKE light should light for 2 seconds. If it does it is not in sleep mode. If it does not light, then either it is in sleep mode or the PKE module is bad.
I got to ask do you know how to operate you FOB and put it in and out of sleep mode?
Try to program you FOB. See if the car will go thru the proper steps with the PKE light indicating the proper signals. If the car won't go thru programming, then the PKE module may be bad because the FOB will not prevent the car from trying to program the FOB.
Having a spare FOB to try this would be the first best thing to try with the programming
Thread Starter
Instructor
Joined: Sep 2015
Posts: 164
Likes: 18
From: Fort Wayne IN
Make sure the battery checks 3.0 to 3.2 volts for reliable operation.
The key FOB testers in the part stores don’t work for the C4 Corvette FOBs. This is because they are a passive FOB where no button is pressed to open the doors.
Make sure the car is NOT in sleep mode. When you turn the key the PKE light should light for 2 seconds. If it does it is not in sleep mode. If it does not light, then either it is in sleep mode or the PKE module is bad.
I got to ask do you know how to operate you FOB and put it in and out of sleep mode?
Try to program you FOB. See if the car will go thru the proper steps with the PKE light indicating the proper signals. If the car won't go thru programming, then the PKE module may be bad because the FOB will not prevent the car from trying to program the FOB.
Having a spare FOB to try this would be the first best thing to try with the programming
The key FOB testers in the part stores don’t work for the C4 Corvette FOBs. This is because they are a passive FOB where no button is pressed to open the doors.
Make sure the car is NOT in sleep mode. When you turn the key the PKE light should light for 2 seconds. If it does it is not in sleep mode. If it does not light, then either it is in sleep mode or the PKE module is bad.
I got to ask do you know how to operate you FOB and put it in and out of sleep mode?
Try to program you FOB. See if the car will go thru the proper steps with the PKE light indicating the proper signals. If the car won't go thru programming, then the PKE module may be bad because the FOB will not prevent the car from trying to program the FOB.
Having a spare FOB to try this would be the first best thing to try with the programming
Is the FOB able to be programmed to the car if the PKE system is off?
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Thread Starter
Instructor
Joined: Sep 2015
Posts: 164
Likes: 18
From: Fort Wayne IN
Make sure the battery checks 3.0 to 3.2 volts for reliable operation.
The key FOB testers in the part stores don’t work for the C4 Corvette FOBs. This is because they are a passive FOB where no button is pressed to open the doors.
Make sure the car is NOT in sleep mode. When you turn the key the PKE light should light for 2 seconds. If it does it is not in sleep mode. If it does not light, then either it is in sleep mode or the PKE module is bad.
I got to ask do you know how to operate you FOB and put it in and out of sleep mode?
Try to program you FOB. See if the car will go thru the proper steps with the PKE light indicating the proper signals. If the car won't go thru programming, then the PKE module may be bad because the FOB will not prevent the car from trying to program the FOB.
Having a spare FOB to try this would be the first best thing to try with the programming
The key FOB testers in the part stores don’t work for the C4 Corvette FOBs. This is because they are a passive FOB where no button is pressed to open the doors.
Make sure the car is NOT in sleep mode. When you turn the key the PKE light should light for 2 seconds. If it does it is not in sleep mode. If it does not light, then either it is in sleep mode or the PKE module is bad.
I got to ask do you know how to operate you FOB and put it in and out of sleep mode?
Try to program you FOB. See if the car will go thru the proper steps with the PKE light indicating the proper signals. If the car won't go thru programming, then the PKE module may be bad because the FOB will not prevent the car from trying to program the FOB.
Having a spare FOB to try this would be the first best thing to try with the programming
I have tried to turn on the PKE, but it will not turn on (possibly due to the FOB not working?)
I tried to program the FOB. The PKE light does come on (so we know the bulb is good) and blink, but never stops blinking when bringing the FOB within working distance of the car.
Le Mans Master
Joined: Jan 2006
Posts: 5,620
Likes: 206
From: Orlando FL
Sounds like you are doing the right basic things.
Just to be a stickler, make sure the battery (CR2450) is above 3.0 volts. 2.9 volts may not work. As I have has similar situation myself a good battery is so important.
It sounds like you next move would be to try to borrow a FOB, go thru programming and see if light stops blinking, it accepts the FOB and all works.
There are some other things that can affect the programming but you had a working system that stopped so I'm not ready to go off into left field with some in depth troubleshooting.
Just to be a stickler, make sure the battery (CR2450) is above 3.0 volts. 2.9 volts may not work. As I have has similar situation myself a good battery is so important.
It sounds like you next move would be to try to borrow a FOB, go thru programming and see if light stops blinking, it accepts the FOB and all works.
There are some other things that can affect the programming but you had a working system that stopped so I'm not ready to go off into left field with some in depth troubleshooting.
Heel & Toe
Joined: Aug 2018
Posts: 17
Likes: 3
From: Nebraska
Hey Scooter if you haven't tried programming the FOB it doesn't cost anything and it may work. Just follow the instructions.
1. Move all Keyless Remotes out of range of vehicle. (10 to 15 feet) 2. Turn ignition key to the ON position. 3. Push the TRIP/ODO button on the DIC (Driver Info Center) twice. 4. Within 5 seconds, push & hold the FUEL INFO button on the DIC until the PKE light comes on and stays on. 5. Turn the ignition to the OFF position, but leave the key in the ignition. The PKE light will begin flashing. 6. Bring one Keyless Remote into range. The PKE light will stop flashing and stay on to show the code is stored. Move the Keyless Remote out of range. The PKE light will begin flashing indicating the system is ready for the next Keyless Remote. 7. If more than one Keyless Remote is being programmed, move the first Keyless Remote out of range and repeat step 6 for any additional Keyless Remotes. Up to three Keyless Remotes can be programmed. 8. To turn off the programming mode, simply remove the key from the ignition or turn the ignition switch on. 9. The programming mode will shut off after two minutes if. A) You have not programmed any Keyless Remotes. B) Removed the key from the ignition. C) After three Keyless Remotes have been programmed.
OOPS just noticed you have tried programming the FOB....never mind.
1. Move all Keyless Remotes out of range of vehicle. (10 to 15 feet) 2. Turn ignition key to the ON position. 3. Push the TRIP/ODO button on the DIC (Driver Info Center) twice. 4. Within 5 seconds, push & hold the FUEL INFO button on the DIC until the PKE light comes on and stays on. 5. Turn the ignition to the OFF position, but leave the key in the ignition. The PKE light will begin flashing. 6. Bring one Keyless Remote into range. The PKE light will stop flashing and stay on to show the code is stored. Move the Keyless Remote out of range. The PKE light will begin flashing indicating the system is ready for the next Keyless Remote. 7. If more than one Keyless Remote is being programmed, move the first Keyless Remote out of range and repeat step 6 for any additional Keyless Remotes. Up to three Keyless Remotes can be programmed. 8. To turn off the programming mode, simply remove the key from the ignition or turn the ignition switch on. 9. The programming mode will shut off after two minutes if. A) You have not programmed any Keyless Remotes. B) Removed the key from the ignition. C) After three Keyless Remotes have been programmed.
OOPS just noticed you have tried programming the FOB....never mind.
Last edited by S Roche; Sep 24, 2019 at 02:15 PM.
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From: Fort Wayne IN
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I would hate to hear that she is gone. I do know that she mentioned to me that she didn't know how much longer she was going to repair fobs.
BTW, here's a little tidbit that she gave me on fobs.
"Motion wears on battery. If the battery were installed just keep the case keyloop end pointed down to prevent motion trigger and the battery will last near shelf life stored in fob....with plus side up....lots if people instally battery upside down. Ouch."
Last edited by puterami; Nov 19, 2021 at 10:24 AM.
Thread Starter
Instructor
Joined: Sep 2015
Posts: 164
Likes: 18
From: Fort Wayne IN
One of the serious problems with is that the battery thickness standard changed when China started making batteries for companies like Duracell, etc. So, never use anything other than the Swiss made Renata CR2450N which you can buy on Amazon. If you use a different battery, it puts too much pressure on the PC board in the fob and starts breaking the ceramic capacitors.
The last I heard from her was a follow up on my fob around June of 2020. She shipped mine back to me when she had almost recovered from COVID, but still had lingering effects.
The last I heard from her was a follow up on my fob around June of 2020. She shipped mine back to me when she had almost recovered from COVID, but still had lingering effects.
Instructor
Joined: Dec 2011
Posts: 136
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From: pittsburgh pa.
........................................ ........................I JUST HAD FOB FIXED IN DECEMBER, SHE IS ALIVE AND KICKING!!!!!............................ ........................................ .......FYI theres a pke remote on ebay today for a convertible, the internals are the same as a coupe . just a different case. its been on there for 4 hours, cant believe its still available. CORVETTE (RARE) ORIGINAL CONVERTIBLE 1993 1994 1995 1996 SMART KEYLESS REMOTE | eBay there is an aftermatket case available but you must modify it to accept OEM internals Keyless Entry Remote Fob Shell SNAP STYLE Case Fits GM 88960923 93-96 Corvette | eBay........................................ .......... FOR PKE REMOTE REPAIRS CONTACT c4fob@yahoo.com
Cruising
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