No Start - Help With Ignition Switch Replacement
Thread Starter
Instructor
Joined: Mar 2004
Posts: 207
Likes: 1
From: Minneapolis MN
No Start - Help With Ignition Switch Replacement
Looks like I need some help replacing the ignition switch on my '91 auto. I have a no start condition when the key is turned. I have checked out the obvious like battery, starter, VATS, fuses, etc.
I'm suspicious of the switch because when I disconnect the 2-wire VATS connector and check the pair coming from the column I should get the same Ohms reading as the key but I don't get any reading at all. And when I check the ECM Fault Codes I get a H46 (Pass-Key Circuit).
What is the power supply to the switch? How difficult is the switch replacement?
Thanks for any suggestions.
I'm suspicious of the switch because when I disconnect the 2-wire VATS connector and check the pair coming from the column I should get the same Ohms reading as the key but I don't get any reading at all. And when I check the ECM Fault Codes I get a H46 (Pass-Key Circuit).
What is the power supply to the switch? How difficult is the switch replacement?
Thanks for any suggestions.
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
VATS won't allow the starter to crank by not closing the start enable relay completing the circuit from the ign sw (crank contact) through the clutch safety switch (gear selector sw if automatic) and then to the starter solenoid on the starter if the correct pellet resistance is not measured. You may not have a problem with the ign sw, but rather with worn contacts in the lock mechanism that connect to the pellet. Proof is your open circuit reading on the wires from the steering column. You need a new lock which will have new contacts that connect to the pellet. You can temporarily bypass VATS by connecting a resistor the same value as your pellet across the 2 wires that come out of the wiring harness (these go to the VATS module). You can use a 1/4 watt 5% resistor from Radio Shack. Don't permanently bypass VATS because 99% of thefts are done by bashing the column and jumping the ignition.
Thread Starter
Instructor
Joined: Mar 2004
Posts: 207
Likes: 1
From: Minneapolis MN
Thanks for the reply. I did try the VATS bypass using a 3.3 ohm resistor connected to the wire pair going to the firewall, same results. I appreciate any other info.
If I check the resistance of the pair coming from the colum with the key in the ignition, shouldn't it give me the same ohm reading as the pellet in the key?
If I check the resistance of the pair coming from the colum with the key in the ignition, shouldn't it give me the same ohm reading as the pellet in the key?
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
With the key in the ignition, the 2 wires from the steering column should measure the same as the value you measure across the pellet in your ignition key. 3.3 ohms is not a correct value. The list below are the standard values for the pellet resistance in ohms.
402, 523, 681, 887, 1130, 1470, 1870, 2370, 3010, 3740, 4750, 6040, 7500, 9530, 11800.
The pellet can be plus or minus 4% from these nominal values. Measure the resistance of your pellet and buy a standard value resistor pack (I think they come in packs of 4) from Radio Shack and measure them, and chose the one closest to the one in the list above and connect it across the 2 pin connector on the wires coming out of your wiring harness. Do not plug the 2 pin connector from the steering column into the wiring harness connector. Then try to start your car. It should start if the resistor you connected is within 4% of the nominal value. A dealer can replace the lock.
402, 523, 681, 887, 1130, 1470, 1870, 2370, 3010, 3740, 4750, 6040, 7500, 9530, 11800.
The pellet can be plus or minus 4% from these nominal values. Measure the resistance of your pellet and buy a standard value resistor pack (I think they come in packs of 4) from Radio Shack and measure them, and chose the one closest to the one in the list above and connect it across the 2 pin connector on the wires coming out of your wiring harness. Do not plug the 2 pin connector from the steering column into the wiring harness connector. Then try to start your car. It should start if the resistor you connected is within 4% of the nominal value. A dealer can replace the lock.
