Electronics Need help wiring something up? Thinking of adding an electrical component to your car? Need help troubleshooting that wiring glitch?

Pass Key Decoder Module

Old 05-19-2008, 10:57 PM
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Pass Key Decoder Module

The other day I had a problem starting my car. It would turn on but no crank. We assumed it was the starter. Shelled out $84 and got that replaced. Wasnt the problem, but it needed to be replaced so no worries at all. Next guess was the Starter/enable relay. Found it after abut three hours coated in what appeared to be melted electrical tape (courtesy of the people i got this car from. I don't like them.) We tested the relay and it was fine. We cleaned it off, and attempted to diagnose the problem from there. We grounded the wire leading to the pass key decoder module and got some crank from the starter. Basically we need to find out how to get the module fixed and where it is located. please help. It's a 1991 Chevy Camaro RS
Old 05-19-2008, 11:16 PM
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Re: Pass Key Decoder Module

There's a good chance it could just be the piece in the ignition cylinder that reads the resistance from the chip on the key. Search this site for the word "VATS" (no quotes) and read up on it. It's simple to bypass if you want to go that route.. IF I remember correctly, a code 51 from the computer points to a bad vats module. Have you pulled the codes yet?
Old 05-20-2008, 09:29 AM
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Re: Pass Key Decoder Module

No I havent. Im slightly new to this. How would i go about that?
Old 05-20-2008, 01:50 PM
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Re: Pass Key Decoder Module

Under the driver side dash there is a plug, it's called the OBD, or ALDL plug, depending on who you ask. Either way, put a jumper between pins A and B.

Ignore the writing around that pic. It's not related to this.

It can be a paper clip, or a short piece of wire, whatever. Put it in with the key in the off position, and then turn the key on. Now, watch your service engine light. It's going to blink out sequences of numbers. To start off, it's going to blink 1 time, then twice. this is a "12". It's going to do this 3 times for each code stored in the computer. Code 12, is always there, it's to let you know you are now in "diagnostic" mode. After the code 12 flashes out 3 times, get ready to start counting. Write down the sequences that it flashes out.
After you get all the codes, turn off the key and remove the jumper from the OBD plug. Then compare them to this chart, and see what you got. Post back and lets us know what you found.

Quote:
DTC - 12 No distributor reference pulse (diagnostic test active)
DTC - 13 Oxygen sensor circuit open or no activity
DTC - 13 Left bank O2 sensor circuit open or no activity
DTC - 14 Engine coolant temp sensor error (high temp indicated)
DTC - 15 Engine coolant temp sensor error (low temp indicated)
DTC - 16 System voltage too low
DTC - 17 Camshaft position sensor error
DTC - 21 Throttle Position sensor error (signal high)
DTC - 22 Throttle position sensor error (signal low)
DTC - 23 Intake air temp sensor error (low temp indicated)
DTC - 24 Vehicle speed sensor error (open circuit or no activity)
DTC - 25 Intake air temp sensor error (high temp indicated)
DTC - 28 Auto transmission range pressure switch error
DTC - 31 Wastegate solenoid circuit error
DTC - 32 EGR system failure
DTC - 33 MAP sensor circuit error (signal high indicating low vacuum)
DTC - 34 MAP sensor circuit error (signal low indicating high vacuum)
DTC - 35 IAC problem or idle error
DTC - 36 MAF sensor error
DTC - 36 24x Crankshaft position sensor circuit error
DTC - 37 TCC brake switch circuit error
DTC - 39 Clutch switch circuit error
DTC - 41 Ignition control error
DTC - 41 MEM-CAL error
DTC - 41 C³I Cam Sensor Signal error
DTC - 42 Ignition bypass circuit error
DTC - 43 Knock sensor error
DTC - 44 Oxygen sensor error (lean condition indicated)
DTC - 44 Left bank O2 sensor error (lean condition indicated)
DTC - 45 Oxygen sensor error (rich condition indicated)
DTC - 45 Left bank O2 sensor error (rich condition indicated)
DTC - 46 Pass-Key II (VATS) system error - circuit out of freq range
DTC - 51 PROM error
DTC - 51 Incorrect MEM-CAL
DTC - 52 Fuel cal-pak incorrect or missing
DTC - 53 System voltage too high
DTC - 54 Fuel pump circuit low voltage
DTC - 55 ECM error
DTC - 58 Trans fluid temp sensor circuit error (low voltage)
DTC - 59 Trans fluid temp sensor circuit error (high voltage)
DTC - 61 A/C system performance
DTC - 63 Right bank O2 sensor circuit error
DTC - 63 MAP sensor circuit signal voltage high (low vacuum indicated)
DTC - 64 Right bank O2 sensor lean exhaust indicated
DTC - 64 MAP sensor circuit signal voltage low (high vacuum indicated)
DTC - 65 Right bank O2 sensor rich exhaust indicated
DTC - 66 A/C pressure sensor circuit error (low pressure indicated)
DTC - 67 A/C pressure sensor circuit error
DTC - 68 A/C clutch relay circuit error (shorted to ground)
DTC - 69 A/C clutch relay circuit error (open circuit indicated)
DTC - 70 A/C pressure sensor circuit error (high pressure indicated)
DTC - 71 A/C evaporator temp sensor circuit error (low temp indicated)
DTC - 72 VSS signal circuit error
DTC - 73 A/C evaporator temp sensor circuit error (high temp indicated)
DTC - 75 Digital EGR solenoid #1 circuit error
DTC - 76 Digital EGR solenoid #2 circuit error
DTC - 77 Digital EGR solenoid #3 circuit error
DTC - 79 Transmission fluid overtemp
DTC - 80 Transmission component slipping
DTC - 82 3x Crankshaft position sensor circuit error
DTC - 85 PROM error
DTC - 86 A/D error
DTC - 87 EEPROM error (flash memory error)
DTC - 90 TCC error
DTC - 93 Transmission pressure control solenoid circuit error
DTC - 96 Transmission system voltage low
DTC - 98 Invalid PCM program
DTC - 99 Invalid PCM program



Last edited by titan; 05-20-2008 at 01:56 PM.
Old 05-20-2008, 02:15 PM
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Re: Pass Key Decoder Module

Measure the resistance of the chip or pellet in the key.
Buy a resistor that falls with in the values on this table:

http://shbox.com/1/4th_gen_tech2.html#pass_key

Locate the small wires under the steering column and install the resistor.
The wires are small and white with orange heat-shrink.
I have made resistors that will simply plug in here for when and if I have a VATS problem.
The wires are small and over the years they break inside the steering column.
the "shbox" site, though its primarily 4th gen, has alot of valuable infirmation on the VATS system.
Old 05-28-2008, 12:26 PM
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Re: Pass Key Decoder Module

say you just wanted to do away with the theft system what is the frequency of the fuel enable, and could you make a simple 555timing circuit to put out that frequency
Old 06-03-2008, 08:50 AM
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Re: Pass Key Decoder Module

just in case anyone else reads this the vats system puts out a 50hz signal to the pcm and a 30hz signal in sone newer models
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