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So I had some issues with the the resistor bypassing my vats. My key ohm’d like 3815 so that’s the size I bought resistors for. When I put it back in place the wire reads 2707 with the resistor hooked up. I pull the resistor and it tests normal by itself. Something is causing it to bleed off. Anyone have a clue? 93 Trans Am WS6.
I just posted a response to your other post in the Firebird section so that may help. However, since there is no 3815 ohm resistor commonly available, I'm curious what resistors you used and how you connected them (series or parallel). That could help explain the discrepancy in readings. The other thing would be that you installed the resistor across the disconnected ends of the key sensor wires on the side going to the BCM (not to the ignition cylinder).
I just posted a response to your other post in the Firebird section so that may help. However, since there is no 3815 ohm resistor commonly available, I'm curious what resistors you used and how you connected them (series or parallel). That could help explain the discrepancy in readings. The other thing would be that you installed the resistor across the disconnected ends of the key sensor wires on the side going to the BCM (not to the ignition cylinder).
thanks for your response, I went with 3900 ohm resistors with a 5% tolerance. I hooked it up just like it was done before. What would make the ohms drop once it is hooked up? Should I add another resistor in place to make up for it? Thanks again for your help!
There are a lot of variables when measuring resistance. I suspect that whatever is causing your reading to differ between installed and out of car is also what's causing the VATS issue. The 3900 ohm resistor is not ideal but its certainly within the tolerance of the system so it should not be a problem. Forgive me if the following sounds too basic but I have to start at the beginning before moving on to more involved diagnosis.
Let's start with where the resistor is installed. Here is a photo of the sensor wires connector near the base of the steering column:
VATS key sensor wires
You want to have that connector unplugged and the resistor inserted across the white/black and purple/white wires (soldering is best but any method which ensures a tight connection will work). Some people cut the connector off and then use crimp connectors to connect the ends of the resistor to the wires. Of course, make sure it's all insulated with electrical tape or shrink wrap to avoid any possible shorts. The other end of the connector with the two white wires in the orange sheathing should be left disconnected and tucked away out of sight.
The other question is where are you taking your reading when the resistor is installed? Taking it directly across the ends of the resistor should give almost exactly the value of the resistor. Checking it at the BCM will tell you what VATS is seeing which could be different if there is a problem in the wiring. That would be an immense help if everything else checks out.
I’m taking the reading at the connection, where the resistor is tied to the wiring. My car had this previously done and started having issues. Turned out the wires were loose on the resistor. I pulled it out and soldered it in. After soldering it, it no longer worked.
Ok, I went back and looked at the initial reading of the key as well as at the original resistor. The key reads 3815 ohm's and If I am reading the old resistor right it is 750K or 7500 Ohms. It ran with the original resistor but security light would flash and sometimes it wouldn't start. Ended up just being loose then quit working when I soldered it in place. Am I just being retarded or does something seem weird? Thanks!
You need clean surface for measuring with a meter and for soldering. Looks like solder globbed around black goop. That will lead to a bad connection and increased resistance.
If I'm reading this right... looking at the bands on that resistor...
Violet = 7
Green = 5
Black = 0
Brown = x10
Which totals 7500 ohm
So I guess your meter read that right.
If your key is reading half that and that let the car start, but the key is half that and the car won't start with that key, then that is the wrong key and you should ignore its value. You might have a bad connection instead.
You need clean surface for measuring with a meter and for soldering. Looks like solder globbed around black goop. That will lead to a bad connection and increased resistance.
If I'm reading this right... looking at the bands on that resistor...
Violet = 7
Green = 5
Black = 0
Brown = x10
Which totals 7500 ohm
So I guess your meter read that right.
If your key is reading half that and that let the car start, but the key is half that and the car won't start with that key, then that is the wrong key and you should ignore its value. You might have a bad connection instead.
I'm going to throw a 7500 back in it tonight and see if that will work. Thanks for the help!
Is it possible that the loose connection of the original resistor also caused a second resistor to drop out? There is a 7500 ohm resistance value in GM's 15 standard values list but there is also the 3740 value which is commonly created by two 7500 ohm resistors in parallel. So, if using the single 7500 ohm resistor ends up not working, you might want to put a second one alongside (connected in parallel) and see if that works. It would explain the key value you're seeing although VIP1 is correct - it could be the wrong key and the VATS bypass would make the key value irrelevant.
Thanks I didn't get a chance to look at it last night. I inherited a huge assortment of resistors but nothing was marked or labeled so I spent quiet a few hours testing them with my gauge.
The color coding on resistors is a standard. You can google a chart. I don't have it memorized. I googled it to check the one in your pic above. I always double-check with a meter too anyway. Usually Resistors come in bands/strips with label/note on the edge indicating their rating. Otherwise, sorting though it is tedious. Hopefully you helped your future self with some organization.
The color coding on resistors is a standard. You can google a chart. I don't have it memorized. I googled it to check the one in your pic above. I always double-check with a meter too anyway. Usually Resistors come in bands/strips with label/note on the edge indicating their rating. Otherwise, sorting though it is tedious. Hopefully you helped your future self with some organization.
Yea definitely. My uncle had just thrown them into some small containers. It's gonna take some time, I won't be doing it right now but one day I'll get them sorted out. Thanks
If the car starts with the 7500 ohm resistor, then that is the wrong resistance in that key. But since you have the bypass, the car doesn't car about the resistance of the key. My guess is that the previous owner changed the BCM or bought the wrong key blank. Either way, the bypass was needed.
09-25-2021, 05:45 AM
93 TA VAT issue 
