dr bob

That connector is used on car without catalysts to adjust fuel mixture range. The potentiomere that plugs in there replaces the function of the oxygen sensor. Oxy sensors die a quiet painfull yet quick death when leaded fuel is used.

Bottom line: Nothing plugs in there on your US car.

dr bob

Diagnostic plug on the '89+ cars is under the cover next to the right-side seat. Round multipin connector with a thread for a retainer of some sort.


Did you do the ohm meter tests yet? POST YOUR RESULTS PLEASE.

Lizard928

Bob is correct,
That 3 pin black plug is for a potentiometer for the non cat cars to adjust the base CO level.
It is normally disconnected.

fraggle

Oops, I was wrong with the purpose but right that it isn't normally connected to anything.

Sorry man!

88porsche928

someone please let me know is relay IV is the ignition monitoring relay and the center top connection is where i plug the multi meter into

88porsche928

actually can some one please explain the ignition monitoring relay and 1a, 1b? i am assuming the top center one on relay IV is the 1a

88porsche928

i have a feeling i did this all wrong but here goes nothing

Red wire on pin 18 and black wire on top center of relay IV is -3.4
red wire on pin 18 black wire on right middle of relay IV is -3.4
red wire on pin 18 and black wire on bottom center of relay IV is -3.3
red wire on pin 18 and black wire on left middle of relay IV is 1
when the red wire from the multi meter is on pin 18 and the black wire is on ground the reading is - 3.6
alright when i plug the red wire in the top center of relay IV and the black on ground its 0.0
when i plug the red wire on the right side middle of relay IV and black on ground its 0.0
When I plug the red wire on the bottom center of relay IV and black on ground its 0.0
When I pug the red wire on the left middle of relay IV and the black on ground its -1

88porsche928

I am assuming that terminal 1A is is the hole that is in relay IV when I take the relay out, can some one confirm this?

dr bob

Dan, the ignition monitoring relay is mounted on a metal frame that holds the two engine controllers. This is right side of the passenger's footwell just forward of the door. There's a carpeted cover there with a snap. Pull the cover off and there's the relay on the bracket surface facing the driver's side, under the EZK brain. The relay is held to the bracket with a U-shaped retainer.

The connections to the relay are on the forward face, a socket that is not captive to the frame. They should be ID'd on the socket once you get it pulled from the relay. If you can't see any terminal markings, look for a red-with-green-tracer wire for terminal A1, and a red-with-yellow-tracer wire for terminal A2. (see WSM section 97, Model 89 Sheet 10, at coordinates J82, for these connections and wire colors. On the diagram, the relay is labelled "IGNITION CIRCUIT CONTROL" at the top center of the page at H81.)



The LH brain is the one closest to the door, sandwiched between the metal support frame and the car body. That's the connector you disengaged, the one you are connecting to terminal 18 (brown wire with red tracer) in the swing-away connector for the test.

Relay IV is not part of any of the testing you are doing.


Make sure that you are measuring OHMS with your meter, the monitoring/protection relay is removed, and all the injectors are still connected in the engine bay. The battery in the car is NOT connected. Test and post your results please.

88porsche928

STATUS, i removed the ignition monitoring relay and disconnected it from the connector, their are not markings on the connector itself however on the monitoring relay is see: 61, a2, 15, a1, 87, 31, e2, al, and e1. i looking in the manual and im not exactly sure if the colors are abbrievated and the diagram is not 3d so its kind of throwing me off.

dr bob

Looking at the relay and the socket, you should be able to determine which pin goes in which slot. You are looking for A1 and A2 for this initial testing, and should be able to confirm your choice by looking for he correct wire color entering the socket slot from the other side. With the battery disconnected and only the meter as described, there's no possibility of damaging anything if you accidentally probe the wrong slot in the socket. This is very basic electrical troubleshooting/testing, and it takes much longer to type the descriptions here than it takes to do the actual testing.

The auto parts stores sell little male spade crimp-on connectors that you can stuff on the socket if your meter probe doesn't fit. Not a bad idea to make three 14ga stranded wires maybe 6" long with one of those connectors on each for this testing. You'll need two (for A1 and A2) now for the narrow-it-down tests described previously, and the third MIGHT be needed for Wally's test if everything passes the ohms tests I described. We won't even get started on that description until we do the ohms testing and see the results.

Mrmerlin

this might make testing easier by following these instructions you should be able to figure out whats working
Thanks to DrBob for posting this
Quote:
Originally Posted by dr bob View Post
The meter tests I shared are extremely definitive when diagnosing harness problems on '89+ cars. Did you find a short in the harness, an open circuit, or a short to ground? If not, it's possible to create new problems while 'fixing' the old harness, where no problems existed before.



Test procedure simplified:

-- With the ignition protection relay out:

A1) Ohms between LH connector 18 and relay socket terminal 1A should be about 4 ohms. Much more means an open in a connector, injector coil, or a broken conductor in the harness.

A2) Ohms between LH connector 18 and relay socket terminal 1A (same test...) should be about 4 ohms. Less than 2 ohm means you have an internal short between conductors in the harness. This is the damage you reported when cutting open that first connector boot.

B1) Ohms between LH connector 18 and relay socket terminal 1B should be about 4 ohms. Much more means an open in a connector, injector coil, or a broken conductor in the harness.

B2) Ohms between LH connector 18 and relay socket terminal 1B (same test...) should be about 4 ohms. Less than 2 ohm means you have an internal short between conductors in the harness. This is the damage you reported when cutting open that first connector boot.

C) Ohms between LH connector 18 and ground should be infinite. If they are less than 1 ohm, you have a short to ground on the LH side of the harness, and it could be at any injector.

D) Ohms between LH connector 18 and ground should be infinite. If they are around 4 ohms, you have a short to ground on the power side of the harness, and it could be at any injector. Proceed to E1 and E2 to narrow down where it might be.

-- E1) Ohms between protection relay socket at 1A and ground should be infinite. If they are less than 1 ohm, you have a short to ground on the power side of the harness, and it could be at injector 2, 3, 5, or 8.

-- E2) Ohms between protection relay socket at 1B and ground should be infinite. If they are less than 1 ohm, you have a short to ground on the power side of the harness, and it could be at injector 1, 4, 6, or 7.



*** Do these tests BEFORE you remove any of the injector connectors. The resistance values presume that you still have all the injectors plugged in. Each injector coil is real close to 16 ohms. Two coils connected is about 8 ohms, 3 connected is a little over 5 ohms, four connected is 4 ohms. On the '89, the harness is separated on the power side and is fed through those two contacts on the protection relay; with the relay removed they are connected only on the ground (LH brain) side, and to the brain through LH terminal 18. With that protection relay installed, the power sides are connected to each other through the relay contacts, and also to the heating coil on the oxygen sensor, even when the LH power relay is not energized.


PLEASE POST WHAT YOU FIND WITH YOUR METER.

88porsche928

pin 18 to a1 4.3
pin 18 to a2 4.4
pin 18 to 87 13.75
pin 18 to 31 16.32
a1 to ground 16.4
pin 18 to ground 16.42

dr bob

You have something grounded in the FI harness. A1 or A2 or 18 to ground (actual circuit 31 which is the ground bus, not always the 31 pin on a relay) should be infinite. Did you measure to ground, or to a relay socket 31? The 31 socket for that protection relay is in fact ground, so if that's what you tested you can start looking for the stray ground in the injector harness.

I'm also not clear in why there would be any continuity between 18 in the LHA connector and 87. Which 87 did you test to? If to the 87 on the protection relay socket, this means nothing except confirming that there is still a ground someplace in the FI harness. The 87 on that socket is shared as power with several other loads that ultimately offer conductivity to ground -- when the LH connector is attached to the controller--. Can you confirm that the test you did 18 -> 87 is at 87 on the protection relay, and that the reading is in OHMS, and not MEGOHMS?

88porsche928

Dr. bob. My multi meter is on auto. I have an idea, its going to take a couple hours to complete