Pontiac Problems? Ask a Mechanic for Answers ASAP
Are you getting a positive power on the trigger wire to the relay from the pcm or a ground?
Yes that is the trigger wire. The computer should turn it into a ground to activate the relay. I have to step out for just a few minutes. If you don't mind let me try to go run an errand real quick and get back to my desk computer. Then we can try and go over what's really going on and try and find your problem. That why I shouldn't have positive power on it ever.
You have to fuse power source is going to the relay. Then the computer as a ground to complete the circuit to activate the relay and then the relations positive power out the fourth part To the fuel pump
I'm sorry that should be two fused porch I'm driving down the road please let me get back to my desk so I can help you.
The pcm gives the relay its ground, there are two fused power sources to the relay, one is hot at all times, the other is hot when the ignition switch is turned on. The the 4th pin of the relay will be hot when the pcm gives the relay a ground signal. the 4th pin goes to the fuel pump.
Let me pull up the wire diagram for this car. If you look on the relay it will have a 87a,87 and so on. With you saying pin 1, 2 and 3 I do not know what pin is what. There is no ground feed to the relay except for the ground from the pcm. You will have two pins with 12 volts with the ignition switch on, the wire to the fuel pump will have a ground on it, but that is from the fuel pump itself, and last you will have a dead lead from the pcm that will turn into a ground when the pcm comands the fuel pump on.
The only problem with that is the fuel pump may keep the relay active and keep running.
With the ignition switch off, how many pins in the fuse box with the relay out have 12 volts to them?
also check it with the ignition switch in the run position please.
Now check it again but this time turn the ignition switch to run please.
Now with the ignition switch on, see what pins have a ground please. You will need a helper to see if you have a ground to two pins, onw will be constant but the other will only have a ground for 5 seconds or less.
I did not ask for an ohms reading. I need to know what pins Have a ground on them. Hold your red test lead to the battery positive post, and check he pins with your black test lead with the relay out please. Make sure you have your meter set to dc volts.
I am sorry, but when you give me information that tells me nothing instead of what I asked for, you are wasting your time. Did pin have a ground for at least 4 seconds after the switch was turned to the run position?
You are not making any sense. You said that pin 3 had 12 volts on it with the ignition switch off, but in your last post there is no mention of pin 3????? You still have not told me what pins have a ground on them. If you do not want my help please tell me and I will see if another expert can help you.
I do my job and do it well. I have helped people that did not even know what a digital volt meter was fix there cars, men and women. I have even helped an older man rebuild a transmission over the internet. You want me to help you then please do as I ask and do not try to over think this problem. What I was looking for was a signal from the pcm to the relay. with all the information you have given me, the pcm trigger wire does not have positive power on it EVER. NJow if you would like to have me help you then just say the word, ME OR ANOTHER EXPERT.?
From what I have seen it sounds like you have had the relay in the fuse box but not all the way down and trying to test it that way. The only problem with that is the relay is giving you back feed and voltages from the fuses not the pcm.
Now I feel like a fool. I just looked up the wire diagrams for this car and it is totally different than most gm cars. the pcm does send a 12 volt power source to the relay. and this should activate the relay. we know that you have the 12 volt constant hot, so that means that the ground to the relay has to be bad, or the relay itself is. I am sorry if I made you feel bad, but that was not my intentions. I just wanted you to slow down and stop over thinking the problem. Can we keep working on this to find your problem? You do not have to pay me for the help.
Please understand that I am working with more then 10 people at a time and when half of them do not do the tests I ask for, it only takes more time to get to the root of the problem.
No the pcm is sending out the 12 volts to activate the relay. What we need to find out is why you do not have two grounds at the relyas pins. You should have the ground from the fuel pump And I am assuming that would be pin 1 according to the data you sent. Please look back over your responses where you said pin 3 had 12 volts?? But in the later data you omitted pin 3??? Please help me understand this.
If pin 5 goes to the fuel pump, why does t not have a ground? The ground should come through the fuel pump and back up to the relay. Do you have a test light? can you connect it to a good ground and probe pin 3 and see if the light comes on for 5 seconds and then goes out?
Ok but your readings say that there is no ground coming from the fuel pump to the relay correct?
And what about this question? Do you have a test light? can you connect it to a good ground and probe pin 3 and see if the light comes on for 5 seconds and then goes out?
Yes that is correct. There should have been 12 volts to the pin for at least 5 seconds. Can you do one more test for me please? Do the same test but this time along with th test light use your digital volt meter and see if you have any voltage with the test light connected and then with the test light disconnected form the battery.
I hate to say it but it sounds like something has either rubbed through the trigger wire, chewed through it, or the solder joints in the pcm have come loose and you are not getting the full amperage though the wire to the relay. The first thing I would do would be to check the pins in the pcm plug as well as run the wire back from the relay to the pcm and see if there are any wire rubbed almost through or chewed through. If you can not find any problem with the wire or the connector at the pcm, then the problem will have to be in the pcm. I am 90% sure that you will find a bad place in the wire from the relay to the pcm.
You are very welcome.