NO spark - lots of diagnosis within...**FIXED**

[hardtailcfl]

Re: What do these plugs tell you?

Re: What do these plugs tell you?

In my books that wire is EST Electronic Spark Timing and the IGN BY is the tan wire under the dash.

Ok that makes sense then and explains why the tan/black wire needs to be disconnected when setting base timing. I'll check the white wire tomorrow and go from there. Thanks again :tup:

 

[hardtailcfl]

Re: What do these plugs tell you?

Re: What do these plugs tell you?

Checked the connections at the ECM and all looks good.

Is there any way to test the WHITE wire going from ECM to distributor? Should it read volts? If so, how many?

 

[Don W.]

Re: What do these plugs tell you?

Re: What do these plugs tell you?

Remove the C + B term and check volts at C and + (the 2 nearest the middle of the module) and post results.

I'm taking this from the flow chart in my manual. Lotta different steps depending and I don't want to type them all. :rotf: However allot of them end up with "replace module" so if you think the coil is good then have that module checked if you haven't done so already.

 

[hardtailcfl]

Re: What do these plugs tell you?

Re: What do these plugs tell you?

Remove the C + B term and check volts at C and + (the 2 nearest the middle of the module) and post results.

Are you referring to the ignition module or ECM?

I just had both ignition modules tested and they were both good.

With that being the case I think it's safe to assume the problem lies within the ECM or the white wire running from ECM to ign module. Is there a way to test the ECM?

After that I guess I have no choice but to trace the white wire....

 

[SY2455]

Re: NO spark - lots of diagnosis within...

Re: NO spark - lots of diagnosis within...

When you remove the 3 term connector on the Dist that Don was talking about "It should be the 1 on the left side of the distributor". Measure the Voltage at the wires mark + and C like Don said with the key on.

What do you get ? A. 10 volts or more, B. Both term's under 10 volts, C. Under 10 volts "C" term only.

 

[hardtailcfl]

Re: NO spark - lots of diagnosis within...

Re: NO spark - lots of diagnosis within...

When you remove the 3 term connector on the Dist that Don was talking about "It should be the 1 on the left side of the distributor". Measure the Voltage at the wires mark + and C like Don said with the key on.

What do you get ? A. 10 volts or more, B. Both term's under 10 volts, C. Under 10 volts "C" term only.

There's a 4 term connector and 2 term connector plugged into the dist so I'm assuming you are referring to the 4 term connector.

Voltage at each terminal with key on is as follows...

A - blk/red = 0.03 volts
B - tan/blk = 0 volts
C - ppl/wht = 0 volts
D - wht = 0.14 volts

 

[SY2455]

Re: NO spark - lots of diagnosis within...

Re: NO spark - lots of diagnosis within...

OK you need to get the reading from the 2 term connector. It should be mark with +, C, B.

 

[hardtailcfl]

Re: NO spark - lots of diagnosis within...

Re: NO spark - lots of diagnosis within...

Ok the 2 term connector is marked A and B on the weatherpak and comes from the top of the coil into the dist.

A - pink = 11.85 volts
B - white = 11.85 volts

Are we talking about the same connector? I don't see anything marked +, C, B going to or coming out of the distributor.

 

[SY2455]

Re: NO spark - lots of diagnosis within...

Re: NO spark - lots of diagnosis within...

Are we talking about the same connector? I don't see anything marked +, C, B going to or coming out of the distributor.

Yes we are talking about the same 1, In 1 part of the manual it is call 1 thing and in the engine wiring harness it is call another. The +, C, B is most likely marked on the module.


Reconnect the dist term. With the key "on" check voltage from tach term to gnd (term. may be tape back in harness.

You should get ?, A. Over 10 volts, B. Under 1 volt, C. 1 to 10 volts

 

[NecroWolf]

Re: NO spark - lots of diagnosis within...

Re: NO spark - lots of diagnosis within...

have you pulled the cap to verify the distibuter is turning? maybe you tossed the timing chain

 

[SY2455]

Re: NO spark - lots of diagnosis within...

Re: NO spark - lots of diagnosis within...

I assume he did that already.

 

[hardtailcfl]

Re: NO spark - lots of diagnosis within...

Re: NO spark - lots of diagnosis within...

have you pulled the cap to verify the distibuter is turning? maybe you tossed the timing chain

Yup...good to go :tup:

 

[SY2455]

Re: NO spark - lots of diagnosis within...

Re: NO spark - lots of diagnosis within...

Brb, PM me will you will be back on.

 

[hardtailcfl]

Re: NO spark - lots of diagnosis within...

Re: NO spark - lots of diagnosis within...

Yes we are talking about the same 1, In 1 part of the manual it is call 1 thing and in the engine wiring harness it is call another. The +, C, B is most likely marked on the module.


Reconnect the dist term. With the key "on" check voltage from tach term to gnd (term. may be tape back in harness.

You should get ?, A. Over 10 volts, B. Under 1 volt, C. 1 to 10 volts

OK gotcha...found those markings on the module. Makes a bit more sense now...

I unfortunately had to shut it down for the night :rant: I'm not by the truck anymore but I'm not sure I understand what you mean when you say "tach term to gnd"? Is there another connector inside the harness that you're referring to? If so, what color wires am I looking for?

BTW...can't say thanks enough for the help I've gotten here. NO question I will soon be a "donating member" :lol:

 

[SY2455]

Re: NO spark - lots of diagnosis within...

Re: NO spark - lots of diagnosis within...

By the way I seen where you posted that you checked the coil. 6 years ago I had a 1982 S-10 that I put a 4.3 engine with a Auto in it. It ran like a top for 200,000 miles then one day going down the road there was a big boom and the truck died in the fast lane at 80 mph. I got the truck to the right shoulder after crossing 4 lanes of freeway in this state of mine, where people just don't like you to change lanes.

It turn out that the coil went to ground and blew a hole in the side of the case where it is wrap by all the steel mounting bracket.

I put a new one in and today that engine is now in my daughter 1988 S-10 short bed truck with a 5 speed with 320,000 miles on it. To this day it still doesn't burn oil and the compression on it is 165 lb still, oil press is still running 60 lb on the road and 20 lb at a stop. I used 5w-50 Syn oil in until the 300,000 mile mark then change it to 15w-50 Syn oil.

 

[SY2455]

Re: NO spark - lots of diagnosis within...

Re: NO spark - lots of diagnosis within...

OK gotcha...found those markings on the module. Makes a bit more sense now...

I unfortunately had to shut it down for the night :rant: I'm not by the truck anymore but I'm not sure I understand what you mean when you say "tach term to gnd"? Is there another connector inside the harness that you're referring to? If so, what color wires am I looking for?

BTW...can't say thanks enough for the help I've gotten here. NO question I will soon be a "donating member" :lol:

To borrow a quote from a friend. The trouble shooting section indictate that there may be another connector inside the main harness under the hood, but you can use the following. If Dave P happen to look at this maybe he know more about the location of the other connector.

There are two white wires on the coil. The one in the gray connector, that goes into the main harness is the tach wire.

 

[hardtailcfl]

Re: NO spark - lots of diagnosis within...

Re: NO spark - lots of diagnosis within...

By the way I seen where you posted that you checked the coil. 6 years ago I had a 1982 S-10 that I put a 4.3 engine with a Auto in it. It ran like a top for 200,000 miles then one day going down the road there was a big boom and the truck died in the fast lane at 80 mph. I got the truck to the right shoulder after crossing 4 lanes of freeway in this state of mine, where people just don't like you to change lanes.

It turn out that the coil went to ground and blew a hole in the side of the case where it is wrap by all the steel mounting bracket.

I put a new one in and today that engine is now in my daughter 1988 S-10 short bed truck with a 5 speed with 320,000 miles on it. To this day it still doesn't burn oil and the compression on it is 165 lb still, oil press is still running 60 lb on the road and 20 lb at a stop. I used 5w-50 Syn oil in until the 300,000 mile mark then change it to 15w-50 Syn oil.

The big boom you're describing is literally exactly what happened. I was on the interstate cruising along at 70 and BOOM no power.

I checked 2 different coils I had and bought a 3rd brand new one just in case. Still no spark

To borrow a quote from a friend. The trouble shooting section indictate that there may be another connector inside the main harness under the hood, but you can use the following. If Dave P happen to look at this maybe he know more about the location of the other connector.

OK I know the wire/connector you're referring to. Guess I didn't realize there was another connector inside the harness specifically for that gray wire?? I'll check it out next time I'm by the truck.

 

[hardtailcfl]

Re: NO spark - lots of diagnosis within...

Re: NO spark - lots of diagnosis within...

OK this may be a long shot but I'm leaning towards the ECM being bad?? Would this work as a test?

If the HEI module is completely out of the system (ie weatherpak connectors unplugged) in theory shouldn't the ECM throw a code 42?

Or another example would be to take out the memcal and the ECM should throw a code 51?

So the million $ question I'm trying to answer is will the ECM throw the corresponding codes if something is not present in the system? Or only throw codes when something is malfunctioning?

And if it should throw a code and it doesn't is it safe to assume the ECM is junk?

 

[DaveP]

Re: NO spark - lots of diagnosis within...

Re: NO spark - lots of diagnosis within...

If you have no spark, it is NOT the ECM. The module sends reference pulses to the ECM. The ECM uses these to trigger fuel delivery. The engine will not start with the 4-wire connector disconnected. There will be spark (everything working normally), but it will not start because there is no fuel injection.

What is the resistance of the pick-up coil? Disconnect the 2-wire connector from the module inside the distributor. Measure ohms across the green and white wire. Should be 500 to 1,500 ohms. "un-changing value".

 

[hardtailcfl]

Re: NO spark - lots of diagnosis within...

Re: NO spark - lots of diagnosis within...

If you have no spark, it is NOT the ECM. The module sends reference pulses to the ECM. The ECM uses these to trigger fuel delivery. The engine will not start with the 4-wire connector disconnected. There will be spark (everything working normally), but it will not start because there is no fuel injection.

What is the resistance of the pick-up coil? Disconnect the 2-wire connector from the module inside the distributor. Measure ohms across the green and white wire. Should be 500 to 1,500 ohms. "un-changing value".

DaveP to the rescue :tup: Good to know about the ECM. I am not by the truck now so will be checking pick up coil tomorrow evening. Thanks!