Transistor by the coil in the car question

[mzeitlin3348]

I have a transistor with the stamp: 2D18
on it. Does anyone have an idea what transistor this is?

It is used as a switch apparently for the coil (on and off) of my 280Zx
It looks just like a power amp transistor and it is heat sinked accordingly.

Any idea what it is? (and where I can buy one!@!)

Thanks

 

[EchoWars]

That's not a valid number that I've ever heard of...and it may not be 'a' transistor, but a monolithic regulator IC instead. The shop manual should tell you.

 

[mzeitlin3348]

The shop manual says, "transistor pack". It looks just like a power transistor with the classic metal case grounded to a heat sink with two pins coming out of the flat base. It is used to 'fire' the coil. This part receives signals from the on-board computer and causes the coil to fire. Apparently it is not working very well (intermittent problem) (sound familiar !!! - must be Houston humidity).

To replace it on a 1983 Z car will cost $165 !!!

I can't help believe that there must be a part or series of parts I can buy which do the same thing....

 

[jpdylon]

Time to hit the bone yards...

Its just a switching transistor used to trigger the pulses for the Ign coil. It was a primitive form of 'electronic ignition'

 

[mzeitlin3348]

Perhaps I can substitute with a typical transistor today?

 

[EchoWars]

Pull the part out and see if it measures on a diode tester like a transistor.

 

[Chad Hauris]

Usually a transistor either works or it doesn't...the few intermittents I have seen in transistors have been thermal. Are you sure there isn't a problem somewhere else such as in the pickup coil in the distributor or in one of the connectors from the pickup coil?

 

[Eric H]

NAPA lists a control module (picture),

ECH TP190
Ignition Control Module $240.65 List
EngineAspiration:Turbo;
Comment: w/ Engine Code L28ET w/ Electronic Distributor

ECH TP108 .
Ignition Control Module $494.96 List
EngineAspiration:Naturally Aspirated;
Comment: w/ Engine Code L28E w/ Electronic Distributor

I don't think they ever charge the list price, at least I would hope not.

I would change the coil too as insurance. Echlin #IC83

 

[mzeitlin3348]

I saw that - but the cost !! It is higher than at the dealer.

I know its not the distributor because the problem is intermittent with long stretches with the car working.

I am not sure the transistor is actually 'bad'. I think it may just be bad contacts for the pins (corroded perhaps?). I can't get to the pins, they are sealed inside this plastic thing, with connectors on top.

and it does test like a diode.

 

[mzeitlin3348]

New Information:

I took the distributor wire off and cranked the engine - as expected - no spark.
BUT ---

When I turn the key to off (shutting down the car's systems), I noticed a spark at the coil, sometimes two sparks ! What's causing this?

Cranking - no spark (sometimes anyway - it worked a bit yesterday, not this morning). Cut the power to the engine and the coil discharges, sometimes twice. It seems the discharge corresponds to the crank of the engine - In other words as I shut the engine off, momentum still turns the engine one or two cycles (the distributor rotor is moving from one cylinder to the next).

Why is the coil discharging when the key is turned OFF?

By the way - I am getting great info here since you are all electronics buffs. Although I am talking about a car - it is still an electronic circuit.

 

[Reel 2 Reel]

I had that same thing with an old Sunbird I once owned...and was having problems with...


Needless to say ...I got rid of the damn thing...

 

[usedto]

I always like to go back to the basics before getting too technical. Cranking on an engine draws tons of power from the electrical system, and can rob the coil of power. GM cars had this problem, so a jumper wire was added to the solenoid to resolve the problem during cranking. I don't know about your particular car, but it sounds like the same thing is happening. That moment you let off the "start" position allows the coil to energize. I would seriously check any ground straps that may have broken or been removed from the engine. You might even try a ground jumper from the distributor just as a test.

 

[Eric H]

It could be the pick up coil inside the distributor, they can go intermittent easily.
Try checking it for continuity when the problem happens. Usually they have a couple thousand ohms.

 

[EchoWars]

I always like to go back to the basics before getting too technical. Cranking on an engine draws tons of power from the electrical system, and can rob the coil of power. GM cars had this problem, so a jumper wire was added to the solenoid to resolve the problem during cranking. I don't know about your particular car, but it sounds like the same thing is happening. That moment you let off the "start" position allows the coil to energize.

Close, but you're missing something even more basic...the coil fires when the key is shut of because that's how it is designed. When the key is turned on, the coil primary has 12V. The ignition system is designed to interrupt that 12V in order to induce the HV in the coil secondary winding. If you simply give the coil primary 12V, nothing special takes place. Turn the key off, and the primary collapses, inducing HV into the secondary.

Point is, the spark at turn-off doesn't mean much, except that the coil works.

 

[CarlV]

I just noticed this, make sure your distributor shaft bushings are not worn out.(common) If the reluctor and stator hit each other you will have no spark.
A misfire at mid/higher rpm's is the very first symptom of this. The transistor at the coil works or not, no intermittant there. Same with the pickup coil in side the disributor. This can be verfied with a plugged in soldering iron within the magnetic field of the pickup coil.


Carl

 

[Lefty]

I once had a Sansui 9090DB with the same symptom

Lefty

 

[mzeitlin3348]

When the car starts (flip a coin) - it runs like a top - especially at high RPM. Idle is rougher but steady (could be missing a spark or two every so many RPM's). When I shut off the car - almost certain it won't start again for awhile...then starts.

When I check the spark - and the engine is ready to start, the spark is synchronous with the engine timing and healthy (big , juicy spark), but only for 5 or six revolutions. It eventually dies away and then sparks when the key is turned off (from start to run that is).

The transister is suspect because of something EchoWars mentioned to me a few weeks back when I replaced a power amp transistor on my Kenwood (driver stage). Transistors can get weak...and when they do - intermittent problems can crop up. I think that is what maybe happening here. Also - it is possible there is corrosion on the pins (which I can not see or get to).....

I'll know more after I do the ohm test. I assume the 'base' is the metal case ....

 

[mzeitlin3348]

But what if the transistor is weak....could that cause the intermittent nature.

EchoWars is correct about the coil...it is always at 12V (on the primary) when the key is turned on. And when I turn to start, the 12V is interupted causing the secondary spark. Testing reveals that. According to the manual, the transistor is a power transistor amplifying the signal from computer. It is a trigger.

I have a new part coming in the mail in a few days. ... we'll see if that fixes it.
If not....then it is something else!??

I heard someone say, "anyone can drive a new car". I am just glad it's not my wife getting stranded in this thing. And this car is so beautiful. (as is the wife).

 

[LBPete]

You must have a 280ZX Turbo if it has the naked power transistor on the coil. The 280 Turbo was the first Nissan model with the ECCS engine control system. This system was eventually used on all injected Nissan models but it was pretty high tech in the early 80s.

This system doesn’t use a typical reluctor type distributor that was used in the non-turbo version and other Nissan models of the era. The ECCS ignition system is controlled by the same control unit that regulates the fuel injection. The ECU monitors crankshaft position with a crank angle sensor. The 1981 turbo used a magnetic sensor that mounted behind the crank pulley. It read tabs on a steel disc behind the pulley. The ’82 and ’83 models used an optical sensor in the distributor. This type of optical sensor was used in all the EFI Nissans up to the mid ‘90s when the VQ engine returned to using magnetic sensors.

It is unlikely the transistor is causing your troubles. Those things are nearly bullet proof. The wiring harness is much more likely to cause the type of intermittent problem you are describing. It is a pretty complex harness in that car. Over time, splices in the harness as well as connector pins will corrode.

The crank angle sensor puts out two square wave based signals that have to travel from the engine compartment to the ECU in the driver’s kick panel. The ECU puts out a pulse signal that switches that power transistor on and off to fire the coil. The power transistor simply switches the coil ground performing exactly the same function as a set of points. If either of the crank angel signals or the transistor control pulse is distorted, you get a misfire. You can watch these signals with an oscilloscope.

With the engine running, try shaking the engine harness anywhere you can move it. There should be a bundle of wire that goes from the engine to the fender and on to a big grommet in the firewall. This stretch of harness is prone to breaks because of the flexing that occurs when the engine rocks and the heat of the turbo.

Shake the hell out of it. If the misfire starts or stops while shaking the harness, you are on the right track. If you can isolate it to a particular area, split the harness open and look for splices and for breaks in the wires inside the insulation. The splices are just crimped with a brass band. Usually soldering will fix intermittent connection in them. Breaks in the insulation are tougher to find. They need to be repaired by cutting and splicing in a section of wire. It’s important to add a piece of wire. Otherwise it will pull apart again as the engine moves.

The 280ZX turbo is one of my all time favorite cars. It’s a real blast to drive. Is yours a stick or an automatic?

- Pete

 

[LBPete]

Looky what I found. This circuit diagram is from a 1982 model. It has all the pin locations for the ECU. You want to make sure you have clean square wave signals into pins 8 and 17 and a clean pulse to the base of the power transistor, pin 5.

- Pete