Clod_King
1/2 ton status
Thank you Dave. I am hitting up the scrappers tomorrow. So I am going to test some wires, and pluck the "C/D" connector, and associated wires for practicing on.
CK5
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Just a few wires left...
- Thread starter Clod_King
- Start date
Clod_King
1/2 ton status
Alright. I got the connector, and getting the wires out is pretty darned easy... Hahaha.
So while I was at the scrap yard I ran into a mechanic, and started to chat with him about my dilemma. He told me that the whole TBI system runs on 5 volts... Is that true?? And if so, I have been running mine off of the straight 14.4 V off the battery. Could that really mess up my whole system??
So while I was at the scrap yard I ran into a mechanic, and started to chat with him about my dilemma. He told me that the whole TBI system runs on 5 volts... Is that true?? And if so, I have been running mine off of the straight 14.4 V off the battery. Could that really mess up my whole system??
dave w
1/2 ton status
The ECM has a voltage DC to DC converter / voltage regulator. Battery voltage is converted to 5 VDC for sensors like the TPS, CTS, and MAP. The 5 VDC should always be 5 VDC, engine running, or engine turned off.
dave w
dave w
Clod_King
1/2 ton status
Do you know which wire supplies power to the MAP sensor?
Or if there were any computer changes from 89, to any other year??
And could I do a lot of damage to my system if I start rearranging my wires?
Edit:
I just went outside, and switched those two wires. It changed nothing. Was kind of hoping it woulddo something different... but no.
Could my EST be ruined?? I mean could I have bumped it by accident during the engine swap and ruined it?? Or when I ran the polarity backwards, maybe I fried it then... Ha. I'm going to pull one of those this weekend, and try that out.
Or if there were any computer changes from 89, to any other year??
And could I do a lot of damage to my system if I start rearranging my wires?
Edit:
I just went outside, and switched those two wires. It changed nothing. Was kind of hoping it woulddo something different... but no.
Could my EST be ruined?? I mean could I have bumped it by accident during the engine swap and ruined it?? Or when I ran the polarity backwards, maybe I fried it then... Ha. I'm going to pull one of those this weekend, and try that out.
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dave w
1/2 ton status
****Gray (ECM C14)
**** Don't know - I'll need to look at some of the other diagrams I have - Could take a day or so to get back to you.
**** OH YES, it would be very easy to damage something if wired wrong
**** Maybe the EST is bad, but I would think the engine would run with an error code.
Clod_King
1/2 ton status
**** OH YES, it would be very easy to damage something if wired wrong
Everything in my wiring setup is the same as the schematic I am using besides the two ground leads A11 and D2. I just reversed them, and it changed nothing...
Ah don't worry about it Dave. I was asking about that because of those wire discrepancies... That's all.
There's gotta be something... I'm going to go through every splice, and replace the ESC saturday and sunday... Maybe I'll find something.
dave w
1/2 ton status
On my schematic A11 is Sensor Return (purple wire) ... OK return is another name for ground, but A11 is the purple wire going to the MAP Sensor on my schematic.
On my schematic D2 is Sensor Return (black wire), but D2 is going to the Coolant Temp Sensor and Throttle Position Sensor. I'm not an Electronics Engineer, but I think the ECM circuit board might have separate ground paths for the sensors using the internal 5VDC power supply? From what I know about Electronics, it might be the ECM reads the sensors (TPS, MAP, CTS) using something called a voltage comparator circuit. I know things inside the ECM are very very complex,
which is why the wiring harness can not have anything wired wrong.dave w
Clod_King
1/2 ton status
My MAP sensor return wire was going to D2, and my TPS/CTS return wire was going to A11...
Complete opposite to what my schematic says... And I tested several trucks at the scrap yard aswell, and they were consistant with the schematic.
I never messed around with wire pin placement during the swap. But I did switch those two wires yesterday, and it changed nothing. Truck starts the same, and dies the same....
Does this computer sound odd at all to you??
SERV. NO. 1227747 ANLW
86ANLW K390472954
That's the original computer out of the sub. And it was bought for government use straight from the factory. I know the government can get some funky options, but why switch those two wires?? Maybe there are other oddities within the system that require that specific computer... I highly doubt that, but maybe....
Complete opposite to what my schematic says... And I tested several trucks at the scrap yard aswell, and they were consistant with the schematic.
I never messed around with wire pin placement during the swap. But I did switch those two wires yesterday, and it changed nothing. Truck starts the same, and dies the same....
Does this computer sound odd at all to you??
SERV. NO. 1227747 ANLW
86ANLW K390472954
That's the original computer out of the sub. And it was bought for government use straight from the factory. I know the government can get some funky options, but why switch those two wires?? Maybe there are other oddities within the system that require that specific computer... I highly doubt that, but maybe....
dave w
1/2 ton status
No ... Should be normal for that make / model / year vehicle.
I think some basic trouble shooting.
What is causing the engine to die? No more fuel? No more spark?
What do you think about pulling the distributor out of the engine ... then use an electric drill to spin the distributor with the ignition switch in the "ON" position? Maybe you can watch the injectors with a noid light or watch a test spark plug while the electric drill motor is spinning the distributor?
There are several details about this type of testing, but I use this method to bench test EFI stuff.
dave w
Clod_King
1/2 ton status
Okay. I'll try that out before I replace the EST.
I have another question. Do I need to run a ground lead from the ECM directly?? Like from the ECM case, to the body. Somebody told me to do that, and it sounded false... But a lead is a lead right?
And if the tranny is not hooked up to the ECM do you still need the chip for the tranny in there??
I have another question. Do I need to run a ground lead from the ECM directly?? Like from the ECM case, to the body. Somebody told me to do that, and it sounded false... But a lead is a lead right?
And if the tranny is not hooked up to the ECM do you still need the chip for the tranny in there??
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dave w
1/2 ton status
If doing a bench type test (using a drill to spin the distributor) make sure the distributor housing is grounded, and all electrical connectors to the distributor are connected.
The ECM case does not need a ground wire. I've never seen an ECM with a ground wired to the case.
If the tranny is not hooked up, I ground the neutral / park input to the ECM, PIN B 10 Orange wire with Black stripe. This tricks the ECM into thinking the vehicle is always in park or neutral.
dave w
