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Testing the Theft Deterrent Relay (Starter Enable Relay)
I have my Theft Deterrent Relay pulled and want to test it with my voltmeter but need some assistance. Does anyone have a diagram or other pic displaying where to put my test leads so that I can check for the ‘click’ of the relay switch and also check the resistance? Alternatively, if you don't have a diagram and are willing to just tell me what to do (or steer me to another linked article), I would appreciate that info.
Re: Testing the Theft Deterrent Relay (Starter Enable Relay)
the outer two wire are for power in and out. The two small wire one is a passkey ground and the other is power. When the relay is grounded the contacts close and power goes through the larger diameter wires.
Re: Testing the Theft Deterrent Relay (Starter Enable Relay)
Ok, thanks for that info. In the attached pic, you can see the four connector tabs from the relay. Just to confirm....if I connect a 12V battery source to the outer tabs, I should hear the relay switch activate. And if I connect my voltmeter leads to the two middle tabs, that should show me the resistance of the relay. Is this correct?
Re: Testing the Theft Deterrent Relay (Starter Enable Relay)
Sorry, I am not really following this....what do you mean by "trigger"?? I am not good at reading wiring diagrams at all. Are you saying I need to give power to the relay and then check the resistance of the middle two terminals?
Re: Testing the Theft Deterrent Relay (Starter Enable Relay)
The center two terminals should be the coil. Once energized continuity would be between the outer two terminals.
It's a simple single pole single throw (spst) relay.
I have no idea what the coil resistance is .
How a electromagnetic relay works. https://en.m.wikipedia.org/wiki/Relay
Last edited by Tuned Performance; 08-24-2017 at 04:51 PM.
Reason: Wikipedia link
Re: Testing the Theft Deterrent Relay (Starter Enable Relay)
Ok, here is what I did:
Connected the the two middle terminals to my 12 volt battery via alligator clips. The relay clicked and the the circuit closed. I checked the outer terminals for continuity via my digital voltmeter while it was energized (clips still on and connected to battery) and it registered continuity (my meter was providing the audible signal) but then the signal would cut out and come back quickly (it did this several times while I was holding everything as steady as I could.
I disconnected the battery power and checked continuity between the two middle terminals and it was spotty...one time it would confirm and then the next it would not (I tried many times).
Not sure what is going on....I suspect this relay could be intermittently going bad....I have had a problem with the starter not engaging and have narrowed things down to this relay. I know others have had problems with this...it is just hard to know for sure. A new one is about $20 so I am going to get a new one and run similar tests on it with my meter and see if I see the same intermittent results that I saw on this one. If the new one checks out more consistently, I think I found the problem.
Re: Testing the Theft Deterrent Relay (Starter Enable Relay)
Well, replacing the relay did not fix the problem. It started up well several times after I replaced the relay and I thought I had success but then I got a non-start condition but was able to get it started by just trying the key again. It started up pretty well several times after but now, after two weeks of sitting in the garage (battery on trickle charger), I got an absolute ZERO on the start along with some odd clicking noises behind the dash (but those have now disappeared). When I insert the key, the dash lights come on but then when I turn it, I get NOTHING...lights go out and just nothing...
The VATS chips on my keys are in good shape...not rounded down like they were many years ago. I have had this car since 1998 and shortly after I bought it, I had problems with the VATS on the car. I had the Chevy dealership look at it in late 98 and they replaced the "pass-key lock cylinder" and issued me two new keys. Now, this was done around 85K miles and I currently have 135K miles. Is the lock cylinder worn out again after almost 20 years even though the keys are in good shape and the cylinder has not gotten wear and tear from key insertion? Or is something else going on with the VATS?
Re: Testing the Theft Deterrent Relay (Starter Enable Relay)
You can measure the key resistance, then disconnect the key reader wires at the bottom of the column. Two white wires in a orange sheath. They should be about the same. The reader connection in the tumbler often is a failure point. You can also pass the passkey with a hz modulator signal to the ecm or if you contact me I can program it out of your computer chip. https://m.ebay.com/itm/GM-VATS-or-PA...%257Ciid%253A2
If you use the hz modulator the signal goes to pin B6 of the ecm a dark blue wire for 86-89 tpi. Accessory power from a6 pink /blk and ground from a12 blk/white.
Re: Testing the Theft Deterrent Relay (Starter Enable Relay)
If you bypass the starter enable relay completely with a jumper and the car starts every time then you will know its the relay.
You jump the relay connector just like in photo in post # 5.
Use heavy gauge wire and male spade connectors.
I did away with VATS and had to do this and leave it that way so I use electrical tape and wrapped it all well to keep everything together.
This way VATS no longer has control of your starter.
Now all VATS can do is kill the injectors.
So if the car cranks but wont start,take a look at the injectors when you turn the key. If there is no fuel then VATS is acting up.
You can also test the injector connections for voltage when you turn the key.
Every once in a while (like in my case)it is the actual VATS Module that's bad. You can chase your tail for quite a while before you figure that out.
I finally had VATS removed and bypassed the relay, then went with a aftermarket alarm system.
Could not be happier with a car that starts "every" time.
If you not going to keep VATS just leave the jumper in. Be sure to wrap it well and be careful when your messing with it. A lot of amperage running through it when you start the car.
Last edited by Ron U.S.M.C.; 09-24-2017 at 06:40 PM.
Re: Testing the Theft Deterrent Relay (Starter Enable Relay)
Ok, I tested the resistance of the two keys I have and they are both 4.72 kohms. I found the two white wires with the orange sleeves, disconnected it and probed the resistance at the connector with the two white wires and found it to be 4.72 kohms as well. Does that clear VATS as the problem here?
08-23-2017, 01:44 PM
