jjrbus

First I am not a mechanic and do not have electronics background! I have a no start no spark and have followed the FSM as best I can and cannot find a problem. I was able to get a new ignitor and coil to install, which did not solve the problem so returned them.

This is a 93 Cab and chassis, V6 auto with dual rear wheels, for which there is 1 ECM available. Part #89661-35760

Now my choice is have a mechanic of unknown Toyota background and diagnostic ability or replace the ECM

Only 1 Toyota ECM available locally out of a wrecked 95 and that is $300! Wrong part # of course.

So my question is, is there any shade tree mechanic way to test the ECM and could something be wrong that would harm the new ECM?

jjrbus

109 views and no thoughts or opinions?

Terrys87

iTrader: (1)

I do not know the 3.0 but the computers are built the same. I have only had one computer to fail and it was cause it got wet. I would suspect an electrical issue in the circuit and not the computer. It could fail but would be the last thing I would check into. To see if the computer is functioning, I would try this https://www.yotatech.com/forums/f116...t-22re-270857/ to see if the computer is at least doing something.

rustypigeon

I just read your other threads to get caught up as to where you are in this problem. Before you do anything else, check voltage at the ECM between terminals W and E1. This will determine whether the CEL is not grounding because of an internal problem, or it is not grounding because the ECM ground circuit is faulty.

Go to this link, page EG2-196 and follow the flow chart with ignition on.
http://htftp.offroadsz.com/marinhake...86troubles.pdf

I read in another post of your that you could not get your probe into the ECM terminal to backprobe it. Just stick a pin or a needle into the back of the connector and then touch you multimeter probes to the pin.

jjrbus

This is getting extremely frustrating so your responses are greatly appreciated.

I found the pin trick online and used it to check for pulse at the ignitor. I unplugged the ECM and checked it first with a continuity tester to make sure I had contact. The ignition showed no pulse that I could see with a computer safe led logic probe.

The green (ground) was on but no pulse.

I did not follow the flo chart on 196 because it said with the car running and idleing.

For lack of knowing what to do I got another ignitor today and tried it again, still nothing.
Jim SW FL

jjrbus

Just came in from checking there is 12+ V between E1 and W

There is also voltage between W and body ground.

I had checked E1 for continuity to ground before.

rustypigeon

Ok, you ECM is not switching the circuit so we need to find out why. Now try doing the following....

1. Unplug the VAF meter electrical connector, turn ignition on and see if the CEL comes on. Sometimes a shorted VAF will cause this problem.

2. If that does not turn on the CEL, check to make sure the ECM is getting battery power. It recieves + voltage at 3 different terminals called BATT, +B1 and +B.

Page EG2-185 in the above link shows you were they are located on the ECM. They are on the right side in the illustration.

Check the following terminals....
BATT-E1 should give battery voltage at all times.
+B-E1 should give battery voltage with ignition on
+B1-E2 should give battery voltage with ignition on

jjrbus

I have already checked those terminals and all is as it should be, unplugging the VAF does nothing.

I also tested the VAF with the following results. All on the 20K ohms scale

0 Vb-Vc 0.27
1. E2-Vs 0.29
2. E2-Vc 0
3. E2-Vb 0.27
4. E2-Tha 1.82 85°
E1-Fc open

I will double check everything when the sun comes up.


I just realized that I missed 2nd comment on this!

1. The resistance measured in Test 3 should add up to the resistance measured in Test 2 plus the resistance measured in Test 0.
2. The resistance measured in Test 1 should be less than the resistance measured in Test2
   

jjrbus

Double checked, did all tests on 2K scale except 4, 4 showed 0 ohms on 2K and 2.4 on 20K at 75°

MAF

0. Vb-VC 281
1. E2-Vs 342
2. E2-Vc 0
3. E2-Vb 281
4. E2-Tha 0 on 2K 2.4 on 20K
5. E1-Fc Infinite

While I am on the MAF There is a connector missing inside the plug, it does not appear that there was ever anything there?


Batt-E1 12.9V all the time
+B-E1 12.63V with ignition on
+B-E2 12.49V with ignition on

rustypigeon

The connector is normal. There is no wire going to the #3 terminal.

Did you get a chance to check for + battery voltage getting to the ECM as described above?

jjrbus

Yes it is under the picture

Batt-E1 12.93V
+B-E1 12.63V
+B-E2 12.49V

Way better to do with the needles/pins!

I'm assuming there is an issue with my MAF? I recheked it before I sent this, the E2-Tha is reading 1437 on the 2000 scale, it is warmer out now, the E2-Vc is still 0

rustypigeon

That reading is out of spec, but I am not sure that in itself is causing the problem.

Try unplugging the center connector from the ECM, this is the one with 16 terminals. This will remove the VAF and its wiring from the equation. Then turn on the ignition and see if the CEL light illuminates.

If that does not illuminate the CEL, the possibility does exist that the ECM is bad, or maybe someone in the past wired a kill switch into the vehicle.

jjrbus

unplugged center connector and no CEL.

Kill switch rang a bell, I had noticed a wire added to the fuse block inside the cab, but thought nothing of it. I chased it down and it is from the ing 7.5V fuse to a aftermarket transmission gauge.

I removed the fuse and took out the ?? like a male spade terminal that was used to tap power from the fuse and put the fuse back in. I noticed the fuse is loose in the socket, wiggled, tapped and prodded, but did not affect the CEL light.

This is a dual rear wheel cab and chassis and takes a different ECM, there is only one available and it is sitting in my garage! From what I have read seems I would be better off sending the OE out for diagnostics and repair?

In the meantime I will look for kill switch. Jim

jjrbus

There was one reman ECM available and it is sitting in my garage. I have sent my OE ECM to http://www.ebay.com/itm/321708270034?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT For diagnosis and rebuild if needed. My only concern is will this be like the transmission shops where everything that comes in needs a transmission?

I do not want to use the reman, not knowing it's history is cause for concern.

Then we get into the issue of did something in the system cause the ECM to fail?
Jim