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1997 wrangler ASD problem!

16K views 24 replies 3 participants last post by  1997jeep1997 
#1 ·
Wouldn't start, saw asd fuse was blown replaced it, started it and drove 1/4 mile and smelt a burn so shut it off immediately and come to find it was 80a fuse instead of 30a!!! Did wiring get burnt or is the pcm fried?
 
#4 ·
So I found that a wire that connected with another going to the incjectors and had another going towards the pcm. The wire that was burnt through the insulation went to the rear o2 sensor. I rewired this into the connector and didn't see any other wires damaged, and still have nothing. Do I need to reset the pcm or could something else have gone bad like injectors or anything?
 
#5 ·
So I found that a wire that connected with another going to the incjectors and had another going towards the pcm. The wire that was burnt through the insulation went to the rear o2 sensor. I rewired this into the connector and didn't see any other wires damaged, and still have nothing. Do I need to reset the pcm or could something else have gone bad like injectors or anything?
What does "still have nothing" mean? Headlights work? Brake lights? Idiot lights on dash when you turn on the key? Starter?

I think you need to print the wiring diagram for the power distribution and grounds and track down where you are losing power. Keep the ASD webpage in mind while you are looking and use it for guidance.

Also keep in mind that something failed to get you in this mess, look for it too.
 
#7 ·
Unplug the black C-2 connector at the PCM. See if you are getting 12v power to pin a22 (red/white wire) & key on 12v power at pin a2 (red/light green wire). If good, plug it back in & with the key on see if you are getting 5v at a17 (orange wire).
 
#14 ·
Brown/yellow wire to sensors gets .7- .8 volts on all sensors and all other wires are getting 5 volts
So a17 is now getting 5v?

If all the sensors are getting 5v to them but no gauges or communication with the date link (OBDII connector) it would seem that either there is a bad wire or wires between the PCM & the cluster/data link or the PCM is bad. Those wires would be the so called “twisted pair” & are white/black & violet/brown.

It is also possible the crank sensor is bad. That can be checked by checking the grey/black wire for a 5v pulsing on & off as you crank the engine, assuming you have 5v at the orange wire & good sensor ground at the brown/yellow wire.
 
#10 ·
You need 5v for several sensors to work as well as the gauges. For voltage to be less than 5 but not 0 I would guess one of the sensors or more likely the wiring between one or more of them & the PCM is shorting pulling the voltage down. The sensors that use 5v are cam, crank, MAP, TPS & speed sensor which gets its 5v from C-3 (white), pin b31 (violet/orange wire) which probably has the same low voltage as a17. Try unplugging each & see if the voltage goes up to 5 to try to isolate where the problem is. Of course check the wiring going to them as best you can given the other melting you had.


This was from a 2003 so wire colors & pin #s may be different but same principles apply.


Need help. 03 Rubicon dead - JeepForum.com


 
#12 ·
Only the speed sensor is from b31, the rest are a17.

I have not seen any that have different voltages on the 2 pins. Always they seem to read the exact same (good or bad) but possible of course. Good idea to check the connector for pin a17 to be sure it is clean & not damaged.
 
#18 ·
The twisted pair sends data from the PCM to the cluster & data link. At the PCM they are c28 & c30 in the C-1 connector. The colors are noted above.

Which “side” of the ASD is not getting power? You should be getting key on power from fuse 11 through the red/light green wire which also powers the PCM (at a2). And the red/white wire from fuse 6 in the PDC should have constant 12v power. If the ASD is not closing, you won’t get power to the coil or injectors or the O2 heaters. The PCM controls it through the ground to the relay & it will only close for a few seconds when the key is turned on unless the engine is cranking & the PCM is receiving a signal from the crank sensor. I think you had one of the O2 wires shorted which started all of this so maybe the fuse is blown. If fuse 6 is good & you are getting 12v to terminal 30 in the relay socket try jumping from there to terminal 87 to bypass the relay & see if it will start.

There is no direct, simple way to test the PCM. It is so complicated & any of many things can fail within it so it is mostly a process of elimination. If everything else checks out you have to assume something inside the PCM is bad.
 
#24 ·
The fuse 11 I referred to is the one behind the glove box & should only have power with the key in the start/run positions. That powers the cluster & PCM (for gauges, etc) & FP & ASD relay coils & some other things. If you have power at the fuse & at the PCM you should OK for that part.

At the crank sensor you should have 5v at the orange wire, sensor ground at the brown/yellow wire & the sensor signal grey/black wire should pulse 5v-0v-5v-0v-5v as you crank the engine. That will tell you the sensor is working & if you get the same pulsing at the a8 pin on the PCM that signal is getting to the PCM.
 
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