dicer

Circuit opening relay feeds B+ term at ecu, 7.5 amp fuse feeds circuit opening relay. ( edit here, disregard this post its not correct)
M rel to EFI main relay.

DeZyn243

Yamae,
Thks for the info.
I had no idea I culd run the ripple test w/o engine operating.
I read the thread for the ripple test and in the note at the top it says "measuring the ripple voltage live while the car is running."
It also says that the vehicle being tested is a 98.
I have a 92 and on my DLC I only have an "Opt" terminal, no other Op... terminals available.

As far as the fuel pressure goes, am I able to check that without the car running as well?
I ask because in Mitchell it says connect the pressure tester and check for specs at idle w/ vacuum (28-34 psi) and at idle w/o vacuum (38-44 psi).
if I can check it w/o being at idle please let me know how to make the connections and the proper spec readings if possible.
The help is greatly appreciated.

DeZyn243

Dicer,
if u look at the attachment photos u'll see that the photos are from the "ECU Power Source" testing section.
I checked all fuses, fusible links and relays in both junction boxes,
one behind the battery and the one under the driver side kick panel.
I even checked the fuses and relays that had nothing to do with the problem just to check them and make sure they were operable.
I supplied power to the relays and the switch closes on all of them.
None of my fuses were blown
I used the meter to make sure that my eyes weren't deceiving me.
This was the first thing that I did before I even thought about the ECU issue.
But if u look at step 7, it says that if it is not ok to check and replace ECU.
That's why I have been stuck on the ECU this whole time

Yamae

You don't need to start the engine. The fuel pump already works when you turn the key to "ON" position. Some models use the term "RUN" instead of "ON" though.

DeZyn243

I'll try that in a few hours then.
Thks

Yamae

Are you sure on the 1st line?
I don't understand the meaning of the 2nd line.

dicer

Here is what I just tested on my one running 90. With key off and not in the switch. At the engine test connector.
My scan tool would not communicate at this connector so not so sure about it.
Heres the volt readings.
Oh and across the battery terminals it tests 12.04 volts
I will update with correct numbers after checking. I used improper ground point.
UPDATES

All terminals are 0.0 volts except for AB with 12.03, and Tc with 11.06

Do you get 12v to the Batt term on the ecu? If not check the EFI 20 amp fuse and power to it, and continuity to the ecu plug.
When the switch closes on your relays is there continuity on the terminals that are switched to?
You may need to back probe the relay coil power source.
If you have power to the Batt term and no power at the B+ the problem is with the EFI relay and its associated circuits. I think the Batt is a keep alive circuit, and after key is on the efi relay really powers it all up, the efi relay sends power to the B+ term.
I now need to do a run test, and may need to probe my in the car test port its not easy to get at with a sore neck too boot.

dicer

Here are the running values
I need to up date these
I did not ground correctly to check the first time so the numbers weren't correct.

HERES THE UPDATE AND CORRECT VALUES and at the engine test port
Battery 14.49

B+ 14.22
Fp 14.15
Vf1 .04
Te1 4.99
Vf2 .03
E1 - .01
Ox2 .92 and this means a bad sensor its unresponsive (other car the sensors respond correctly .1 to .7 or so up and down)
Ox1 .08 must not be good
Ts 4.70
Ab 14.37 on my other 90 this is 0.0 ????????????
Tc 13.27

Other than noted both 1990 with trac read the same one car has no memory seats etc.

Don't know.... The inside test port doesn't have the B+ or some of the other test point.

dicer

Your right Yamae, its not correct it was late when I was looking at the diagram.
20 amp fuse is for the Ecu to the Batt term, Circuit opening relay looks like connects to fuel pump relay. I don't understand the test connector readings I got. (as above wrong ground point for the dmm)

DeZyn243

Okay!
Just got home and I started with supplying +B to Fp and the Fp got no power.
I also tested the readings on my DTC (key off) with 11.80V across batt terminals and got
+B .5mV
Fp .5mV
Vf1 .5mV
Te1 .4mV
Vf2 .5mV
E1 .3mV
Ox2 .6mV
Ox1 .6mV
Ts 5.2mV
Ab .3mV
Tc 10.86V

I checked the voltage at +B previously I got 1.3V on all 3 ECU's.
I will go back and check what I get at the BATT terminal.

As far as the coils and continuity, yes, when I supplied power to the coil, the switch that closes was getting continuity.

I'll give an update here shortly.
Thks for ur help.

dicer

I DID NOT USE MILLI VOLT SCALE, your numbers look normal I would think.

Note I found the reason for my goofy probed values, I did not use proper ground point. So look at the above posts for new numbers.


I am going to check my other 90 and see what it gets unless it rains. Will update.
Yes test that Batt term at the ecu it better be what ever the battery is. I'll have to study more to see what the key switch does to power it up.
I want to know what the fix is for this, just in case it happens to me. So please if you figure it out let us all know. I'm going to keep digging too.

GO TO THE ABOVE POSTS WITH THE CORRECTED VALUES FOR ENGINE TEST PORT .

DeZyn243

Alright, so I have done a few things.
I looked into doing the ripple test that Yamae mentioned but I don't have a connector at the Opt terminal so I was unable to do that step.

So I back probed the ECU for voltage and continuity.
These are my readings.
+B = 1.5V/open
+B1 = 1.5V/open
E1 = 1.1mV/closed
M-REL = 9.9V/open
E01 = .2mV/closed
E02 = .3mV/closed
Circuit Opening Relay = 10.9V/open

As far as the readings I got at the DLC with Key on I got: (1st reading is at the DLC under hood. / The 2nd reading is at the DLC by the driver's side kick panel if the terminal was available).
+B = 1.36V
Vf1 = .59V
Vf2 = .59V
Ox2 = 9.2mV
Ts = 8.9V
Te1 = .59V / 9.4mV
Tc = 12.8V / 319mV
Fp = 7.5mV
E1 = 7.4mV / 6.1mV
Ox1 = 9.7mV
AB = 9.9mV / 3.3 mV

Maybe this will offer some clarity on what's next.

Yamae

+B should be nearly 12V when the key is at "ON" position. 1.5V or 1.36V is too low. DLC's +B is supplied through the main EFI relay. Check the relay getting the DC12V from the battery via the 20A EFI No.1 fuse and supplying it to the ECU (pin No.16 of D connector) and the DLC +B.

DeZyn243

That's why I was originally lost.
The first thing I did when car stopped running was checked my fuses n relays.
I have a brand new EFI relay I just brought Friday.
It tests just fine.
Because my fuses n relays were up to specs I started looking at the ECU a couple of days ago because it was not testing within specs.
I paid for two so far and they both don't test within specs either.
The readings I just posted from the ECU are the same on my original and the the two replacements.
That's why I was lost and originally started the thread asking for help cause I new the ECU's were faulty.
I'm going to go buy another one tomorrow and see how that works out.

dicer

And what did the Batt test at? Probe at the ecu plug, if its not 12 ish ie normal what ever the battery is, then that fused circuit is messed up.