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Discussion Starter #1
Got a 89 turbo harness/smec in a 87 non turbo new Yorker ( I didn't do it)

Ran good for 6 months, randomly died a couple times then restarted. Then, a final time, didn't restart

Found no ground signal ( blue/yellow stripe wire) from computer to asd/fuel pump relay. I wired in a relay to ground it, and drove another 20 miles, then it died again. Took smec apart, SEEMS burnt on one component.

Checked powers/ground to smec, all ok. Installed used SMEC from 89 turbo lebaron. Ran about 15 miles, then lost that ground signal again. Will start if I ground that blue/yellow wire. I've been told to inspect molex pins, how do I do this?

What am I missing? Can anyone tell me through a pic what the component that is possibly damaged, runs?

TIA
 

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That component is custom hybrid array, they are also used extensively on the SBEC as well. I have not reversed engineered them yet as I would need to destroy a few ECUs. It appears to be a combination of resistors and capacitors for signal conditioning, at least for the SBEC2 I disassembled. It is unlikely you can find a reference to the part as usually they are labeled only with a Mopar part number which is not very helpful.

Could you check the error codes on this ECU as it might help us.
 

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Discussion Starter #3
I had code 42, computer isn't reading power from ASD, because bit is not operating.

Do you have any idea what that component actuates at all? Do u need to remove epoxy to see these molex pins connections I've been told to check?

Thanks for your help!
 

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Do you have a Factory Service Manual (FSM)? you are getting at a point that you really need one.
The ASD relay coil activation is a medium current requirement as these are handled by the SST 15 or 16 pin driver chip which is the long black device beside the Orange Electrolytic cap.
My gut tells me something other than the SMEC is causing issues here.
 

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Discussion Starter #5
I put a noid light on, and grounding the ASD relay and cranking, I found the light very dim

All injectors ohmed out ok, but #3 sounded different when i powered it up. I replaced it, still dim light when plugged in. If unplugged, the light of Is normal.

I also found the red/black wire was cut to the air charge sensor, I ran a new one to sme

I also noticed the 2 wires into the coolant temp sensor are frayed going in. I separated them with tape

My noid light is bright now, but no ASD unless I ground it

The chip next to the caplooks ok, it's the ones below that that might be cooked in the old smec

I do not have a fsm, but have downloaded diagrams, and ran through ASD testing, to the point of "replace smec" and I believe also something else is telling the SMEC to turn off
 

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Discussion Starter #8
Am I missing anything that causes the ASD ground signal for 1 second on key up? Still don't have that
1. Powers and grounds good to.logic board, one 8 v source reads 8.6v
2. Clean/inspected computer connection
3. Cleaned, inspected grounds under computer, behind engine, and next to fuel rail

As far as I know, there's no reason I should have lost the ASD ground signal, beyond a another bad computer, but I want to make sure

Thanks again for any help, this is my work vehicle
 

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If your ground circuit is not complete the current will look for an alternate path to ground which could be back where it came from.
Be 100% sure your Main Controller Ground is properly connected to a Clean Metal Surface and Secure.
ELECTRICAL- Main Controller Ground 84-89.jpg
Using an Ohmmeter verify all controller ground circuits have continuity to ground (less than 5 ohms)
SMEC 14 Pin Connector Cavities 6 and 7
SMEC 60 Pin Connector Cavities 5, 15, 16

If all of that checks OK then you can proceed to diagnose the ASD Relay circuit.
The ASD circuit is very simple.
Two power feeds, ground side control and an output to the Injectors, + Coil, Fuel Pump.
RD - Constant Battery Power through a Fusible Link
DB - Switched Ignition Power from the SMEC 14 Pin Connector, Cavity 3
Power in is from the Ignition Switch to SMEC 14 Pin Connector Cavity 4
DB/YL - Ground Side Control
Using your ohmmeter verify continuity to ground on the ASD ground control circuit, Smec 60 Pin Connector, Cavity 58 (less than 5 ohms)
DG/BK - Power Output To Components and SMEC.
Power will only be present for 1 second with initial key on and not again until the controller
sees a crank/fuel sync signal from the HEP with the engine cranking.
If both power feeds are present and you have ground side control and there is no output on the DG/BK wire, replace the ASD Relay.

You can manually actuate the ASD Relay by grounding the DB/YL wire in the Underhood Diagnostic Connector with the Key On to verify output.
6-ASD Manual Actuation.JPG

88-89 SMEC 14 Pin.jpg 88-89 SMEC 60 Pin 1 - 30.jpg 88-89 SMEC 60 Pin 31 - 60.jpg
 

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Discussion Starter #10
Just double checked the grounds in your post, all pass, .06 ohms. #58 does not ground on key up. Powers check out too, it's unbelievable...
 

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Discussion Starter #11
The only other weird think is the #13 5 volts is 8 volts and #52 is supposed to be 8v, and it's 9v. Not sure if that's normal
 

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The only other weird think is the #13 5 volts is 8 volts and #52 is supposed to be 8v, and it's 9v. Not sure if that's normal
This is not good... we need to get #13 back to 5V. Are you comfortable with electronics?
If so we can help you troubleshoot, for now it is best to test "on the bench"
 

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Fairly...I have a modis scope, I know what a cap is etc, but that's were it stops
Excellent. So my first thought is why is the 5V at #13 at 8V. Since the PM board supplies 8V(9V in your case) this means that the voltage regulator circuit is toast. The external demand for 5V is very low as it only powers the MAP and TPS. Remove the 60 way and measure the resistance from pin #13 to ground. I get 530 ohms on my 87 CSX which calculates out to 10mA. If yours is significantly more you likely have a short somewhere. As a side note, do you have a variable power supply to generate 8V if we need it
 

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Discussion Starter #15
I do not have variable power supply, but I have a universal power plug in that has some options for voltage on it, I'll take a look, thanks so much for helping me out! I will check what you asked tonight
 

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Just so you are aware, if the controller is fried and this is not the first one you need to find out why.

GM had a problem back in the 80's with faulty ECU's under warranty.
GM used "quad drivers", one driver controlled 4 components.
They would replace the ECU and it would die a few months later.
they asked their techs to start checking resistance in the circuits affected to check for faulty components that may be killing the ECU's.
That did not solve the problem.
They then asked their techs to activate the circuits and check amperage flow to the failed Quad Driver, that uncovered the faulty component.

Learn from GM, be sure you determine exactly what killed your controller or you will be right back here again.
 

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Discussion Starter #17
#13 to ground is open, no resistance. Key off and key on

I am hoping to find the problem, I believe it's in another component too.

Thanks!
 

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#13 to ground is open, no resistance. Key off and key on

I am hoping to find the problem, I believe it's in another component too.

Thanks!
To clarify my request, measure the resistance from #13 on the 60 way connector to ground. This will check for short circuits on the 5V supply line from the 60 way to the MAP and TPS.
Using resistance is fine to trace shorts on simple circuits.
In Electrical Engineering the rule is "Thou shall always be measuring voltage"
When troubleshooting and measuring voltages it is very important to do so under load. Of course, voltage under load is used to measure current V=IR. As NAJ story above explains, resistance measurements in a complex circuit is nearly useless. I found that out the hard way in the early 70's when I started my training in electronics.
 

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Discussion Starter #19
Found my modis hookup, and hooked on up

Got a waste gate/baro code, but I assume that's from having them disconnected. I did that last night. Code 42 showed up too

2 weird things. Modis shows 11.5 volts at test connection, battery is at 12 ( see pic) also, I can turn in the fuel pump from the modis ( through ASD) but when I go to actuate the ASD, nothing happens
 

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Discussion Starter #20
To clarify my request, measure the resistance from #13 on the 60 way connector to ground. This will check for short circuits on the 5V supply line from the 60 way to the MAP and TPS.
Using resistance is fine to trace shorts on simple circuits.
In Electrical Engineering the rule is "Thou shall always be measuring voltage"
When troubleshooting and measuring voltages it is very important to do so under load. Of course, voltage under load is used to measure current V=IR. As NAJ story above explains, resistance measurements in a complex circuit is nearly useless. I found that out the hard way in the early 70's when I started my training in electronics.

I believe that's what I did? I disconnected the 60 way, probed #13 and the other probe to ground. I show no resistance (open circuit) this is correct, right? Unless I'm misunderstanding you. I see the test is looking for a short to ground, and non was found
 
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