c0wcommander

I recently bought a 90 Camaro RS that has had VATS problems before. Previous owner had fixed it but it appears I've broken whatever fix he did after replacing all the fuses and possibly moving a connection somewhere. When turning the key, the fuel pump runs and the starter cranks, but no ignition. Does VATS also disable the ignition system, or could this be an ignition problem somewhere else?

henryd3

iTrader: (128)

If the starter is turning your problem is something other than VATS. Have you checked for spark at the plugs or coil? You might try that next

c0wcommander

Yes, there is spark. But I am getting an error code 53 though. The odd thing is the starter motor is cranking, could there still be a VATS problem? I found this bit from the Thirdgen VATS article.

If the engine WILL CRANK and a code 53 is displayed, that indicates that the VATS decoder module has detected a correct key resistance, and has grounded the relay coil negative wire for the start enable relay, but that the ECM is not receiving the VATS signal from the module. That can be caused by either a failure of the VATS module output which generates the signal, or Circuit 229 between the VATS module and ECM is open or shorted to ground.

My VATS module is dead? It doesn't make sense considering how I was able to drive the car 30 miles after buying the car. Previosu owner is clueless too, but says that when I changed the battery, it must've reset something.

henryd3

iTrader: (128)

Sorry, don't know anything about the code 53 thing. In my experience a VATS problem would not let the starter turn at all. Have you checked for fuel spraying in the TBI while cranking?

c0wcommander

I'm not sure how to check for that, what's the best way to check it?

camaronewbie

It is possible that the VATS module can ground the starter enable relay but not send the proper signal to the ECM to fire the injectors - it's happened to a few folks. And in your case it's a higher probability, since you have evidence that a previous owner has been screwing with the VATS system ... they may have bypassed the starter enable relay by just giving it a constant ground source.

In this case, you may need to order and install a VATS bypass unit. These units are available on ebay, at Painless, etc. They run about $20 - whatever (you know Painless gets a higher price for their sticker). They install and bypass the VATS module by sending the proper signal to the ECM to tell it that it's OK to fire the injectors. There are two different frequencies available depending on the car - make sure you order one that supplies both if you decide to go this route.

But as mentioned - look to see that the injectors are firing first - they should have a nice conical spray pattern to them. Just remove the air cleaner assembly and look inside the TBI unit at the injectors while someone cranks the car.

c0wcommander

Thanks, I will check it later on. Also, about the VATS bypass unit, isn't there also a home-made one you can make with parts from Radioshack?

camaronewbie

Yes - not sure about radio shack having the parts, but others have made their own. Most of the radio shack mentions you see is where folks do the resistor bypass, which you can certainly try - only takes a $1 or 2 in resistors. The resistor method gives the VATS module the resistance it's looking for so it does it's thing. But if the VATS module isn't properly working, then giving it the right resistance isn't going to make it send the right signal to the ECM.

www.thirdgen.org/vats
www.thirdgen.org/vats_passkey_system

The ECM signal is a pulse wave I think, in a certain Hertz (I think some 50 Hz, some 80 Hz). It is posible to make your own gadget to produce the wave signal, but that's way beyond my electronics knowledge.

c0wcommander

Thanks for the replies guys, but now I finally got her started. It was never a VATS problem to begin with, it was only giving an error code 53 because the wiring to the VATS module was loose. The problem was the ignition control module, it was just too old and needed to be replaced after 20 years. Bought a new one at Autozone for $40 and it started right back up like before.

The strange thing though is that I was able to drive it 30 miles home last week. Did my new battery burn it out? And what else should I replace on the car, should I ditch the distributor cap too and buy a new one? Also the car is now giving out an error code 33, what would I need to replace to fix that?

henryd3

iTrader: (128)

When ECMs start failing they work when cold or for a while after startup, but fail when they heat up. You got home in time. 33 is MAP related. Check for vacuum leaks between the MAP sensor and the back of your TBI ( I'm assuming you have the 5.0 TBI engine ) and that the connector is on solid. If the cap looks good with no carbon tracking, cracks or excessive wear it should be OK, but that's up to you. To insure longest life for your new ECM, I trust you coated the bottom with the dielectric grease provided before installing. Failure to do so will lead to shorter life for it. If you didn't get that or don't have any, go to Radio Shack and get a tiny tube of heat sink compound. It works better

c0wcommander

Yep, I actually used some Arctic Silver thermal paste on it, same stuff on my PC's CPU. As for vacuum leaks, I think one of the vacuum lines is broken, which probably explains the rough idling too. I couldn't find any at Autozone, do they sell vacuum lines specifically for 1990 Camaro RS's somewhere online?

henryd3

iTrader: (128)

None specifically cut to fit, but most parts stores have some of that skinny black plastic stuff. With some fittings or rubber vac line you can set up the ends to fit tight over where they need to go and not leak. I've found them at JYs before, but that depends on your access or availability to one with third gens. Or regular vacuum hose could work as well

c0wcommander

Thanks guys, I found some at NAPA and just installed it. It's idling better now and there are no more error codes. It's running rich though, I think I might have to replace more parts to get the exhaust not smelling like gas so much.