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mix3d_3motionz

mix3d_3motionz

10+ Year Contributor
63
0
Oct 4, 2011
Lewis, New York
I will give a little history on the car. 96 2.0 NT 420a
I bought non running. Owner said car had no spark.

Previous owner also had made a mess of the wiring. I have since removed the engine wiring harness and completely gone through it..making repairs etc everywhere I even seen the slightest defect.

I have replaced the coil, cam sensor, crank sensor, ASD relay, Fuel relay, fuel pump, plugs and wires, and the battery. I did these mostly due to the mileage and after reading the many post of all of these things going bad, I figured I would get them out of the way at the same time.

Before I had replaced anything...I did the key dance and got these codes.

42...I got twice...
42 Fuel Level Sensing Unit Voltage Too High.
42 Fuel Level Sensing Unit Voltage Too Low.
42 Fuel Level Unit No Change Over Miles.
42 Fuel Pump Relay Control Circuit.
42 MFI (ASID) Relay Control Circuit.
42 No MFI (ASD) Relay Output Voltage at PCM.

54- No Cam Signal at PCM.

Here is what I found to be happening.....I have 12 volts at center pin of coil wire for 3-5 seconds as ASD activates with key turned to on. Once cranking however I have 0 volts. Fuel pump primes etc. I believe I just have a no spark while cranking issue.
I did remove battery cable in an attempt to clear the codes, however they are still there even after all the work I have done. I have even bought another used PCM (part number matching) and have been swapping back and forth between the two. SO basically "O great forum" the car is going to the shop next week but if anyone has any ideas I would certainly like to try them before it went and I got butchered on labor charges. Thanks in advance.
 
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In my experience the 420a will not run without the cam sensor. This goes against how common knowledge of fuel injection works, but I would start buy checking as to why you have no cam signal. Many sensors can share a common 5-8volt reference signal so if one is shorted or faulty it causes others on the same circuit to set error codes.
 
Upvote0
make sure the crank sensor is not on upside down. i am not to sure if it can be installed upside down on a 420a but i just went 5 straight days testing everything because of no start which turned out to be the crank sensor was on upside down on my 4g63t..
 
Upvote0
I am not sure if i could of put it upside. The current position is with the end that the connector plugs into is pointing up towards the hood?

BoostedPhoenix said:
In my experience the 420a will not run without the cam sensor. This goes against how common knowledge of fuel injection works, but I would start buy checking as to why you have no cam signal. Many sensors can share a common 5-8volt reference signal so if one is shorted or faulty it causes others on the same circuit to set error codes.
Click to expand...

Kinda figured that may be the case. I do have a 5 volt ref @ the cam sensor.
 
Upvote0
mix3d_3motionz said:
I am not sure if i could of put it upside. The current position is with the end that the connector plugs into is pointing up towards the hood?



Kinda figured that may be the case. I do have a 5 volt ref @ the cam sensor.
Click to expand...

It's been a while since I worked on my old 420a DSM, but it sounds like you need to trace the wire from the cam sensor to the ECU and make sure it's all intact.. It's a long shot, but have you popped the ECU itself open to see if it's still in good shape? The caps on my old 420a were starting to leak a little and cause little hiccups here and there.
 
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Spoolin92GSX said:
It's been a while since I worked on my old 420a DSM, but it sounds like you need to trace the wire from the cam sensor to the ECU and make sure it's all intact.. It's a long shot, but have you popped the ECU itself open to see if it's still in good shape? The caps on my old 420a were starting to leak a little and cause little hiccups here and there.
Click to expand...

I am sure the wiring is fine, I had an extra wiring harness, I went through and repaired any thing that looked like it would cause a problem in the future by soldering and heat shrink. I haven't opened the PCM but I think i will open them both up today and see whats what.

*update* I decided against digging through all that old urethane or whatever my PCM's are filled with. Its old and even when i finally dig to the bottom I can not tell if caps are leaking due to the residue of the junk*

I did however try to jump the red/black to the black/red at the ASID relay connector and still no power at coil pin 2 when cranking. The Cam sensor is brand new but i suppose could be defected. Any ideas on how to test sensors with a multimeter? I don't have access to an othoscope.
 
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Upvote0
Spoolin92GSX said:
It's been a while since I worked on my old 420a DSM, but it sounds like you need to trace the wire from the cam sensor to the ECU and make sure it's all intact.. It's a long shot, but have you popped the ECU itself open to see if it's still in good shape? The caps on my old 420a were starting to leak a little and cause little hiccups here and there.
Click to expand...
Check the ECU against a know good one if at all possible.
 
Upvote0
Sounds to me like you have a blown fuse then or something with similar symptoms, with the power jumped across the ASD relay you should have power whenever the key is on not just cranking.
 
Upvote0
mix3d_3motionz said:
I will give a little history on the car. 96 2.0 NT 420a
I bought non running. Owner said car had no spark.

Previous owner also had made a mess of the wiring. I have since removed the engine wiring harness and completely gone through it..making repairs etc everywhere I even seen the slightest defect.

I have replaced the coil, cam sensor, crank sensor, ASD relay, Fuel relay, fuel pump, plugs and wires, and the battery. I did these mostly due to the mileage and after reading the many post of all of these things going bad, I figured I would get them out of the way at the same time.

Before I had replaced anything...I did the key dance and got these codes.

42...I got twice...
42 Fuel Level Sensing Unit Voltage Too High.
42 Fuel Level Sensing Unit Voltage Too Low.
42 Fuel Level Unit No Change Over Miles.
42 Fuel Pump Relay Control Circuit.
42 MFI (ASID) Relay Control Circuit.
42 No MFI (ASD) Relay Output Voltage at PCM.

54- No Cam Signal at PCM.

Here is what I found to be happening.....I have 12 volts at center pin of coil wire for 3-5 seconds as ASD activates with key turned to on. Once cranking however I have 0 volts. Fuel pump primes etc. I believe I just have a no spark while cranking issue.
I did remove battery cable in an attempt to clear the codes, however they are still there even after all the work I have done. I have even bought another used PCM (part number matching) and have been swapping back and forth between the two. SO basically "O great forum" the car is going to the shop next week but if anyone has any ideas I would certainly like to try them before it went and I got butchered on labor charges. Thanks in advance.
Click to expand...
If you have no spark while cranking,mabe your ignition switch is bad.I had a similar problem and I bought a new ignition switch and it fired right up,problem fixed.under$20
 
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I would start off by checking the cam sensor. I have a 1997 rs and the cam sensor has to be pointing down. Not sure if that makes a difference. If you checked all the wiring yourself and checked sensors, coil pack etc, it can be a key that is on your cam that holes the sprocket. My dad and I rebuilt an engine. It wasn't getting any spark. We did everything possible. Swapped ECUs, coil packs etc and it turned out that there is a pin (key) that holds the sprocket in place. If that is broke, your cam (exhaust) will spill but not to the level where it needs to be. I would sugguest to do everything else because now your dealing with timing....
 
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I found something odd today, At my cam sensor wires, with the key turn on I have 8v on one pin and 5v on another. But should I only have the 5v ref when the engine is cranking? Not a 5v constant with key on? And if I am correct on this, what would cause this?
 
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One pin will be your reference voltage which is constant with key on, another a constant ground, the third will be the signal wire to the ECU which could act as a ground when the key is on. Pardon me that i dont know which order they are in but it sounds like what you have is normal.

If you have a brief power to the coil when the key is turned on then you know the ECU is providing power via the ASD relay, this means the ECU does not realize the engine is cranking. I do recall a TSB stating that certain years may set codes for a cam sensor when the problem is in fact the crank sensor or vice versa. Check to make sure you have these same results at the crank position sensor plug.
 
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BoostedPhoenix said:
One pin will be your reference voltage which is constant with key on, another a constant ground, the third will be the signal wire to the ECU which could act as a ground when the key is on. Pardon me that i dont know which order they are in but it sounds like what you have is normal.

If you have a brief power when the key is turned on then you know the ECU is providing power via the ASD relay, this means the ECU does not realize the engine is cranking. I do recall a TSB stating that certain years may set codes for a cam sensor when the problem is in fact the crank sensor or vice versa. Check to make sure you have these same results at the crank position sensor plug.
Click to expand...


well i went back out and decided to check the crank sensor...i have my 8v, but no 5v. I tried jumping it with the 5volt from the cam sensor, and fuel was priming seemed like i had turned the key to on. So again i am lost. I am not sure if the crank signal should be 5volt constant like the cam?
 
Upvote0
I think I see a problem now that I re-thought about what I said. You were right with the results on the cam sensor plug. The pin you get 5 volts through sounds like it is shorted to ground somewhere. I want you to check this pin for continuity to ground when the ECU is unplugged. I would tell you to try a temporary jumper wire from this pin to the ECU but I cant for the life of me find the page on 2gnt with the ECU pinouts.

Found it. http://2gnt.com/index.php?d=ECU_Pinout
 
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The key in question is a Woodrow pin or a dowel pin which keeps the car in time. You have a crankshaft gear that is joined together the same way... Keeps the proper alignment
 
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