my 89 iroc is getting no fuel pump or injectors pulse. i have tested the injectors with noid lites and no indication. vats seems to work because engine cranks, security lite comes on and goes out. i never see the ses lite , the lite bulb is good. where does the fuel enable signal come from, is it the ecm. what pin number and is the ecm providing the signal/volts or is a component producing the signal.

 

That does not sound like a VATS problem. The fuel pump would still run. It sounds like the is a problem with the computer. Check for all the powers and grounds to the computer. There is a fuse in a holder by the battery you may want to check that and see if it is good. If you need any help with the pin #'s for the powers and grounds let me know and I will look it up. Mike

 

Well it is my understanding is that if there is a vats system problem it will throw a check engine light but im not too sure about that. However in responce to your other questions the vats signal works like this. The VATS madual actually sinks a signal from the ECM to tell it to enable the fuel injector pulse. What the signal is, its is eather a 30 or 50 hz wave with a 50% duty cycle depending on application. Dont know the voltage or the specific pin the signal wire goes to but if you search there is a few detailed write ups on the vats system and how it works. I will say though that it is possable that the signal wire from the vats module to the ECM is broken or has a bad connection and that even though the security light goes out the security light is controlled by the VATS modual and dosnt care if the ECM recieves the everythings ok signal or not only that it was sent. However if im not mistaken this should throw a trouble code that i dont believe is stored.

 

thanks, getting information about the pin #'s and location of components would be helpful. b1 and c16 orange wires from the ecm are not getting voltage. i found the wires are spliced to two larger orange wires of a factory splice and then four wires go separately to fuel pump, maf power, maf burnoff, and another relay i don't know about. those four wire don't have power either. now the fuse for ecm and fuel inj 1&2 have voltage with the key in run/start position.

 

If you have no power on all those wires I would be looking for a open circuit as all those wires are off a common feed direct from the battery and should be hot all the time .
That circuit also supplys the power to the oil pressure switch.

Looking at a simple generic F-body diagram for the "165 ' it notes an inline 20A fuse on that circuit; possibly the one mentioned above.
Need to check for open circuit between those wires and batt +

 

It sounds like a problem with the inline fuse by the battery. Have you found it yet? I will try to get a picture of it later. As a test you could use a jumper wire and connect power to the orange wires and see if the car runs. Mike

 

i have not found it yet. i noticed that a black/red stripe wire that comes from the alternator and connects the the positive battery post terminal. this wire has an inline fuse that has a red wire on one end, a black wire on the other and they connect to the dual coolant fan relays an fan motors connectors. i notice that my battery nevers stays charged.

 

after posting two different threads about this problem, i finally fixed it. that factory splice of four wires into four wires was the the problem. i connected the red wire that might have been that fuse holder connection i never had and now everything works. the fuel pump turns on and the injectors prime and the engine runs, but idles real bad. i know what the problem is, the previous owner removed all the pollution system and components to include the air condition. i probably will have to burn the prom to remove all these systems plus vats. thanks everyone for your help, it was greatly appreciated. i wouldn't have found that splice area without your input.

 

Nice to get somefeedback when someone solves a problem

 

I am having the same problem. Where is the location of thar splice point?