Universal Theft Deterent (UTD) system?????
Thread Starter
Melting Slicks
Joined: Feb 2002
Posts: 2,699
Likes: 2
From: The Black Hole LA
Universal Theft Deterent (UTD) system?????
'90 auto vert.
Can someone explain exactly how this system works. I have an intermitant no start problem. I first suspected the VATS system, but have bypassed that. I was reading in the electrical service manual and there is a section on the UTD. Could a malfuctioning UTD system cause the car to have a no start issue?
I have power to the starter enable relay, but no power coming from it to the starter side. I checked the wire coming from the CCM which is supposed to ground the relay to work and there was no ground, like when the VATS is not working, however like I said I have bypassed the VATS with an inline resistor, and yes I am sure I did that right.
Can someone explain exactly how this system works. I have an intermitant no start problem. I first suspected the VATS system, but have bypassed that. I was reading in the electrical service manual and there is a section on the UTD. Could a malfuctioning UTD system cause the car to have a no start issue?
I have power to the starter enable relay, but no power coming from it to the starter side. I checked the wire coming from the CCM which is supposed to ground the relay to work and there was no ground, like when the VATS is not working, however like I said I have bypassed the VATS with an inline resistor, and yes I am sure I did that right.
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
Better check your bypass job. I doubt the 90 vettes do this, but later C4's require that the ign key be removed between cranking attempts, so permanently putting a resistor across the VATS module will not work.
The start enable relay must close before the starter solenoid can get 12v and the CCM (VATS module on earlier C4's) must see the correct pellet resistance before it will ground the start enable relay.
The start enable relay must close before the starter solenoid can get 12v and the CCM (VATS module on earlier C4's) must see the correct pellet resistance before it will ground the start enable relay.
Thread Starter
Melting Slicks
Joined: Feb 2002
Posts: 2,699
Likes: 2
From: The Black Hole LA
Better check your bypass job. I doubt the 90 vettes do this, but later C4's require that the ign key be removed between cranking attempts, so permanently putting a resistor across the VATS module will not work.
The start enable relay must close before the starter solenoid can get 12v and the CCM (VATS module on earlier C4's) must see the correct pellet resistance before it will ground the start enable relay.
The start enable relay must close before the starter solenoid can get 12v and the CCM (VATS module on earlier C4's) must see the correct pellet resistance before it will ground the start enable relay.
In my manual it says that one wire(gray) coming from the locks is also the "arm" wire. I didn't know what this meant is why I am asking the question. My '86 I was so familiar with did not have this feature so I am unfamiliar with it.
Racer
Joined: Jan 2007
Posts: 274
Likes: 0
From: Muskogee OK
Your problem sounds similar to mine. You'll need to ground terminal G to A on your ALDL to check CCM codes on your speedo display.
Once your grounded, your display should show 1.1, and any trouble codes will show up. It will also cycle to 4, which is for the ECM.
To see if the CCM is reading your bypass correctly, push the Trip/Odo button and scroll to 1.2. Look in the small display of the odometer and you'll see 01. Use the Eng/Met button and scroll to 06. This shows the VATS Key A/D count. If I recall from an earlier post, your key code is 4, so the display should read between 64 and 70 according to the 90 FSM.
If you have a slightly loose or dirty connection at the CCM, you'll get the dreaded intermittent and the display may show different numbers up to 255. Mine would show anything from 216 to 230.
My initial plan was to remove the interior panels and pull the CCM, but I was able to get a finger into this tight area and move the connections slightly. Bingo, all of a sudden, the display changed from 218 to 154, which is in my key range.
I haven't had any problems for 3 weeks ( yup, I just jinxed myself
), so you might try this.
Once your grounded, your display should show 1.1, and any trouble codes will show up. It will also cycle to 4, which is for the ECM.
To see if the CCM is reading your bypass correctly, push the Trip/Odo button and scroll to 1.2. Look in the small display of the odometer and you'll see 01. Use the Eng/Met button and scroll to 06. This shows the VATS Key A/D count. If I recall from an earlier post, your key code is 4, so the display should read between 64 and 70 according to the 90 FSM.
If you have a slightly loose or dirty connection at the CCM, you'll get the dreaded intermittent and the display may show different numbers up to 255. Mine would show anything from 216 to 230.
My initial plan was to remove the interior panels and pull the CCM, but I was able to get a finger into this tight area and move the connections slightly. Bingo, all of a sudden, the display changed from 218 to 154, which is in my key range.
I haven't had any problems for 3 weeks ( yup, I just jinxed myself
), so you might try this.
