22r carb stalls at idle after accidentally "grounding" out the Tach signal... out"
09-05-2003, 08:12 PM
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22r carb stalls at idle after SR5 Tach swap
My truck ran fine until I decided to install the SR5 gauge cluster.LOL!
When I put in the "deluxe" cluster, I may have accidentally grounded out the coil/igniter from the "check" plug connecter. I believe this connecter is the one where you have to run a wire to the back of the Tachometer in the instrument cluster.
After doing this, the truck now stalls at idle speed. I checked all fuses, replaced the coil/igniter assembly, check the signal generator inside the distibutor for proper resistance and even used another ECU control unit I had. The truck still runs the same. It stalls at idle. Ever since I played with the wiring to the Tach gauge it has been stalling at idle. It ran perfect before I did this SR5 tach swap.
The only other thing I can think of is that I shorted something out in the wiring somewhere. Can anyone tell me where I should be looking for the problem in the wiring harness?
The Haynes repair manual states the only three things that may cause stalling at idle are the coil/igniter, signal generator and the ECU control unit. I've already replaced and/or checked all three items, but the truck still stalls at idle ever since I messed with the Tach wiring. That leads me to conclude that there's a problem in the wiring somewhere.
Can anyone give me any clues to what it could be?
Thanks.
-Mike
When I put in the "deluxe" cluster, I may have accidentally grounded out the coil/igniter from the "check" plug connecter. I believe this connecter is the one where you have to run a wire to the back of the Tachometer in the instrument cluster.
After doing this, the truck now stalls at idle speed. I checked all fuses, replaced the coil/igniter assembly, check the signal generator inside the distibutor for proper resistance and even used another ECU control unit I had. The truck still runs the same. It stalls at idle. Ever since I played with the wiring to the Tach gauge it has been stalling at idle. It ran perfect before I did this SR5 tach swap.
The only other thing I can think of is that I shorted something out in the wiring somewhere. Can anyone tell me where I should be looking for the problem in the wiring harness?
The Haynes repair manual states the only three things that may cause stalling at idle are the coil/igniter, signal generator and the ECU control unit. I've already replaced and/or checked all three items, but the truck still stalls at idle ever since I messed with the Tach wiring. That leads me to conclude that there's a problem in the wiring somewhere.
Can anyone give me any clues to what it could be?
Thanks.
-Mike
Last edited by mikedog; 09-06-2003 at 12:48 AM.
09-07-2003, 03:25 AM
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I don't know, how about removing the SR5 gauge cluster, or disconnecting one connector at a time to see if it clears up, then you'll know where to look, maybe.
09-07-2003, 08:52 PM
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Thanks Rob!
That's just it, I have the old "idiot light" gauge back in there for now.
Ever since I messed around with those three wires on the instrument panel harness going to the Tach, the truck runs rough at idle and wants to stall out if I don't press the accelerator pedal to bring the revs up.
When I was "switching" the three wires (yellow/white, black coil wire and ground) on the instument panel harness to the leads to the back of the Tach, the engine immediately ran rough if I connected the three wires in a certain way. I did this about four times then the engine ran rough and stalled no matter what I did after that.
I blew something out, but I don't have a clue what it could be. I've already replaced the coil/igniter and checked the signal generator in the dist. for 140-180ohms resistance which checked out okay.
I didn't burn any fuses or fusible links from what I can tell in my service manual. The ECU seems to be the only thing left. I can't bypass it because the truck won't run with the ECU disconnected. LOL!
I tried another ECU I got at the junkyard but the truck still ran the same. I don't know though, maybe the junkyard ECU was bad too. I just hate to be replacing things in a hit or miss fashion just to find the problem.
All I know is that when I switched around those (3) Tach input wires coming from the instrument panel harness the engine never ran the same after that.
Anyone else have any ideas to what it could be?
That's just it, I have the old "idiot light" gauge back in there for now.
Ever since I messed around with those three wires on the instrument panel harness going to the Tach, the truck runs rough at idle and wants to stall out if I don't press the accelerator pedal to bring the revs up.
When I was "switching" the three wires (yellow/white, black coil wire and ground) on the instument panel harness to the leads to the back of the Tach, the engine immediately ran rough if I connected the three wires in a certain way. I did this about four times then the engine ran rough and stalled no matter what I did after that.
I blew something out, but I don't have a clue what it could be. I've already replaced the coil/igniter and checked the signal generator in the dist. for 140-180ohms resistance which checked out okay.
I didn't burn any fuses or fusible links from what I can tell in my service manual. The ECU seems to be the only thing left. I can't bypass it because the truck won't run with the ECU disconnected. LOL!
I tried another ECU I got at the junkyard but the truck still ran the same. I don't know though, maybe the junkyard ECU was bad too. I just hate to be replacing things in a hit or miss fashion just to find the problem.
All I know is that when I switched around those (3) Tach input wires coming from the instrument panel harness the engine never ran the same after that.
Anyone else have any ideas to what it could be?
07-13-2009, 06:11 AM
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Well- Carbed 22R here with simialr issues.
I think I have run into the same problem. If a 22R diagnostic port is attached to the P tach terminal on the cluster it appears to do 2 bad things:
1. the temperature gauge reads incorrectly
2. once the ECU goes into closed loop the motor will not idle.
I was able to disconnect the tach lead and the motor runs fine now( no tach signal though)- I don't think I hurt anything electrical.
Where exactly did you hook the tach wire to? I tried the diagnostic check port( which worked until the motor warmed up). I also tried a diode on the diagnostic port to see if this would isolate the tach wire and keep it from putting the ecm in "die" mode. It did nothing.
I then tried the yellow wire( which becomes black) at the igniter to body harness(this is shown in two different schematics to drive the tach but it did not drive the Tach on my SR5 cluster).
So I have no tach but it will run cold/hot.
Next I was going to try the black(negative) side of the igniter to coil wiring harness but I am a bit apprehensive as the igniter is probably the most expensive part on the whole truck. Fry that and see how "cheap" this mod really is.
so I could use some help.
Not exactly Plug and play.
Scott
I think I have run into the same problem. If a 22R diagnostic port is attached to the P tach terminal on the cluster it appears to do 2 bad things:
1. the temperature gauge reads incorrectly
2. once the ECU goes into closed loop the motor will not idle.
I was able to disconnect the tach lead and the motor runs fine now( no tach signal though)- I don't think I hurt anything electrical.
Where exactly did you hook the tach wire to? I tried the diagnostic check port( which worked until the motor warmed up). I also tried a diode on the diagnostic port to see if this would isolate the tach wire and keep it from putting the ecm in "die" mode. It did nothing.
I then tried the yellow wire( which becomes black) at the igniter to body harness(this is shown in two different schematics to drive the tach but it did not drive the Tach on my SR5 cluster).
So I have no tach but it will run cold/hot.
Next I was going to try the black(negative) side of the igniter to coil wiring harness but I am a bit apprehensive as the igniter is probably the most expensive part on the whole truck. Fry that and see how "cheap" this mod really is.
so I could use some help.
Not exactly Plug and play.
Scott
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