I was starting to ditch the fusible links today for the fuse upgrade on my SE, and I noticed something odd. I took my voltmeter and grounded the negative lead to the negative side of the battery and probed the contacts with the positive lead for each fusible link. The top one (EFI) has 6volts on one side and 12.5 on the other. The other 4 have 0 volts on one side and 12.5 on the other, which is how it should be, I think. Any ideas? Some of you know that I just recently had a problem where I only had 6v to the relays. That is fixed, but now this.

Mike

 

Mike,

Neither of those measurements are correct. Neither side of any of the fusible links are ground! None should be showing 0v. The only way that 1 side will show 0v while the other side is showing 12v is if the fusible link is blown or is removed. Both sides of all fusible links should be showing ~12v.

 

I read Mike's post as he had removed the fusible links and was probing the empty terminals in the box. Am I right Mike? If so something is supplying partial voltage to the EGI wiring. I'd try unplugging the ECU and rechecking your reading. I have no reason to think that is the problem, but its a simple place to start.

 

Yes that is correct. I took the links out and was probing the terminals. I realize that in my original post I wasn't clear on that--sorry Kent. 74RX4, I will try unplugging the ECU to see what I get. I still welcome any thoughts.

 

I don't if this helps, but the terminal that reads 6v has the white wire with a blue stripe feeding it.

 

One more thing----I disconnected the smaller of the two connectors on the ECU, and the terminal now reads 0v. Plug it back in, and it's back to 6v. I guess I didn't solve my electrical problem after all. I now have a spare ECU, thanks to Kent, and using this ECU did not make a difference in the voltage outputs.

 

Okay. Mike, did you get the ECU? Did you install it? The WL wire that you are talking about goes to the main relay and is then carried through to the ECU (the 'V' terminal that we talked about that was reading 6v). So, it seems as the problem is still there..assuming this is with the new ECU.

Edit: nevermind..you just covered it

 

Mike: When you were probing the fusible links, did you have all 5 of them removed when doing the test or did you remove one at a time? I am trying to figure out where this voltage could be coming from.

If you checked them individually, then I would suspect the main relay for the next check.

 

Kent,

I will go out and do some more testing. I'll be back with you in 1/2 hour.

 

Kent,

I checked them both ways----one out at a time and all of them out, except the main relay link. You may remember that the original problem I had was that I was getting only 6v to the "V" pin on the ECU and only 6v at three out of 4 wires on one of the main relays. It turned out that the EFI fusible link had a bad connection. When I cleaned it up a bit, I got a full 12v at the relays, and now I even have 12v at the V pin too.

I re-checked all the link terminals with the links inserted, and all of them have 12v on both sides. What is odd is that the EFI link terminal reads 12v one one side and 6v on the other side with the link out. The other 4 links will show 12v on one side and zero on the other if the link is disconnected. Maybe I'm poking my nose into something that is normal. Could it be that the EFI link is directly wired to the computer?

 

So, it reads 6v with all links removed except for the main link..is that correct?

That may be okay. I was concerned that you were maybe getting 6v with everything disconnected. If that was the case, something very weird would be going on. If you are getting 12v on both side with everything plugged in, then it imight be okay.

From the diagrams, it looks like you should get 0v with it disconnected and should be the same as if you checked the white wire, but the main link still connected. Since it appears that they are different on the voltage readings (should not be since the pair of main relays are basically identical), you might have some kind of failure in one side of that main relay. I say this because the WL wire runs from the fusible links directly to the main relay and doesn't look like it connects to anything else

 

The V and O terminal that the fusible link-W/l wire-main relay-R/w wire circuit connects to are in the large plug. If voltage is 0 when the large plug is plugged in and the small plug is unplugged... I would think the problem is something that connects via the small plug sending improper voltage into the ECU. Seems like it would not be the ECU or the main relay.

Ron

 

Yes, with all the links removed, except the main, the EFI link terminals read 6v on one side and 12v on the other. This is also true if I reconnect the other three links. I was wondering if you or someone who has an SE could see what you get if you remove the EFI link and probe the terminals? This would confirm whether or not my readings are normal.

 

Yes. I could do that. I need to find where I put my multimeter. I have an FC fusebox in mine, but that doesn't make a difference.

 

Thanks Kent. I did have someone already check their SE, and with the link disconnected, he had 6v on both sides. Now I'm real confused. When you get a chance, I would just like to know what your SE reveals.

 

He can't get 6v on both sides. One side is fed directly from the battery. That side of all links will always have battery voltage. I will see what I get.

What you check, was the ignition turned on or was it off? Could make a difference as that will change if the main relays are energized or not.

 

Key was always on. Keep in mind that if I disconnect the small computer connector I get 0v instead of 6v on that side. There seems to be a series connection between the main relays, fusible links, and computer.

 

I'm talking about the two plugs that plug into the ECU. I understood Mike to say that the voltage went to 0 when the big ECU plug was plugged in and the small ECU plug was unplugged. I am just suggesting it might be something involving a component that feeds or is fed through the small ECU plug. Maybe I'm reading this all wrong. I'll be quiet.

 

I understand what you are saying. I had a look at the small plug and it doesn't look like there is anything there that would likely cause what is going on (at least as far as I can tell). It is possible that he does have some shorted wire or something else like that. Jsut trying to see if I can see a way that this smaller plug could likely talk to the larger plug. Maybe inside the ECU, but the ECU is a known good one that I supplied. Could be external wiring. We'll have to look into it more.

The post that you quoted, I was talking about at the links. He said that he had someone pull the links and test both sides and they were showing 6v at both sides. This can't be as one side is fed directly from the battery.

No need to be quiet. The more input the better. I am just trying to understand exactly how he did the test (ignition ON or OFF) to try to get a better feel as to what is going on. If the key was OFF, the relay should be open and should not be communicating with anything downstream (like the ECU). There is nothing between the link and the relay on this wire, so it would seem to me that something is screwy with the relay. However, I am assuming that the key was OFF when the test was done. If it was ON, then that wire is communicating with the ECU and other devices and a defective part/connection in that area could cause the problem.

The 6v thing sounds like a voltage divider is somehow being setup.

Anyway, that is what I am currently thinking. I'll test it on my car as soon as I can to see what I can come up with.

 

So, key was ON... did you try it with it OFF? If the key was ON, it could be normal, however, I would expect the W wire (other link on that block) to show the same behavior...but maybe not.

 

Mike: Checked mine. It seems like yours is all okay. With the key on, I get 6v on one side of that link, 12v on the other. The other link related to ECU/injection shows 12v/0v

If the key is off, all links show 12v on one side and 0v on the other like they should (links removed).

So, everything should be fine with your setup.

 

Kent, and everyone else that has been helping troubleshoot this problem:

I have been giving you all wrong information that definitely warrants my receiving a good beating. The link that is showing 6v on the one side is not the EFI link, it's the computer link----I'm so sorry. Yeah, it's the link on the very top. I don't know how this will affect all that we have discussed so far. I know that it makes sense now why it goes to zero volts if I disconnect the small computer connector. Here is some more info that may help figure out if I still have a problem or not.

With the key off, and the computer fusible link disconnected, the terminal reads zero. BTW--I'm talking about the terminal that is closest to the rear of car. If I turn the key on, it will read 6v. Another thing I noticed is that when I have the key on and showing 6v on that terminal, and then disconnect the main fusible link, it goes to zero.

Anyhow, please forgive me for the mix-up. Maybe what I'm seeing is normal. Only you guys can confirm that.

 

Yup. Normal. Read my last post.

I was going by wire color, so the fact of what the link is called does not change anything. I think you are good to go.

 

Yeah, it still the white wire with the blue stripe. Thanks Kent and everyone else.