94 ATX no start *UPDATE*

[hawkeye18]

The wiring to the DIS could very well be bad. These wires are old and brittle. I have absolutely no idea which wires go to where from the DIS to the computer, but ohm each of those wires out individually to make sure one of them isn't broken. If the signal wire to the DIS broke in its insulation, your car will die very quickly and very suddenly. I would also suspect the wiring from the DIS to the coil pack. At this point I'm 95% sure it's not a component problem but a wiring problem. Whip out that multimeter and start measuring ohms...

 

[projectSHO89]

Key on. Check for batt voltage at the three pins of the DIS module for the coil signals. If no batt voltage, your primary coil power is missing.

Here's a thread to diagnosing the DIS system. It was posted for the SC, but the SHO system is identical. <coming shortly>

Steve

 

[TimboSHO]

Key on. Check for batt voltage at the three pins of the DIS module for the coil signals. If no batt voltage, your primary coil power is missing.

Here's a thread to diagnosing the DIS system. It was posted for the SC, but the SHO system is identical. <coming shortly>

Steve

I found it.

http://www.frontiernet.net/~miketoni/images/tbird/DISnostart/DIS No Start.htm

I will be going back over there shortly with all wiring diagrams and this step by step diagnosis and see what I can find. Thank you all so far!

 

[TimboSHO]

UPDATE again......

Ok, while testing it with the thunderbird flowchart (that thing is a lifesaver), I discovered a broken wire. It was the R/LG wire right by the coil pack (primary power to coil pack, good call hawkeye18 and projectSHO89!). The wire itself was actually broken off inside the insulation. Since it's so close to the spade inside the terminal, I really need a new spade, but they are obsolete, along with the connector (good thing I know of a parts car .

Now the problem. I was testing resistance in this circuit after I found the break in the wire, and since it's the power for the coil pack, cps, cid and dis, i made sure there was no resistance to Battery +, and there wasn't. But then I tested the resistance of this wire to ground, and it's only 5 ohms! Yikes! So this means that there is also a short to ground somewhere? This may be a little trickier to find as i might have to start taking some wire loom apart to even find this. Any suggestions of where a ground wire comes near this R/LG wire?

Boy, isn't electrical fun

 

[TimboSHO]

I should also add that when I first discovered too much resistance in the R/LG wire going from the DIS to the coil pack, I put a jumper wire between the two and the car started up and ran for about 2 minutes. Then it died and wouldn't restart?

I repaired the wire with a spade/wire extension from a parts harness. I'm still concerned with the low resistance to ground though.

 

[Off Road SHO]

If that wire you found goes into the group of wire that has the shield around it, and the engine has been washed with water at any time, you might have a slight resistive ground fault. Was the wire you tested disconnected at both ends? If not, what is on the connected end? A meter such as a guage on the instument panel, a sending unit? When looking at a path problem, always make sure you disconnect the devices on both ends.

Tom

 

[projectSHO89]

Regarding the wire with the 5 ohms resistance to ground, follow the following procedure to see if it is abnormal or not:

Maintain meter reading at test point to ground. See which disconnect connector removes the "low" reading. Do in this order.

Remove IGN COIL fuse.

Coolant level sensor.

DIS module (both connectors).

CID and CKP sensors.

Coil and RFI capacitor.

CCRM module.

See which one causes the reading to go up by a substantial amount. That will be the component that is leaky or partially shorted.

FWIW, I don't know if 5 ohms is normal or not. It's cold outside and I'm not inclined to go test mine this morning..... However, if you need confirmation of a specific reading, I may make a trip outside.

Steve

 

[TimboSHO]

However, if you need confirmation of a specific reading, I may make a trip outside.

Steve

I think I'll just check my own car and see. My you guys are up early for a sat ha ha, just kidding, I'm just the lazy one! I'll print out your 'disconnect' chart and try that as well Steve. Thanks! I'll let you know what I find!

 

[TimboSHO]

First off, I checked my car, and that 5 ohms must be normal (mine was 7). That was with the key off. With the KO, it went way up to like 4Mohms (on both cars). So I went through the flow chart again from the beginning, and I got to step N28

N28 - CHECK PIP EEC FOR SHORTS TO GROUND

Key off

Disconnect EEC-IV processor from vehicle harness.

Connect LED Test Lamp between (-) (PIP EEC) and Positive battery cable connector.

Key on

If the LED Test Lamp is on, check the connectors, service or replace the harness. Otherwise go to N29.

This is the DB wire pin 56 on the computer.
I get battery voltage when I do this.
Also, I noticed that I get no resistance when I go from the GY wire to the DB wire on the CPS itself with it unplugged? Is this normal? I notice that they are both PIP signals, one for the ICM and one for the computer.
But it looks like i'll have to tear the intake off and tear the wiring harness apart looking for a short in that DB wire. I have another wiring diagram that has a connector C126 in line with this. Anyone know where this is?

 

[TimboSHO]

Ok, I found connector C126 (gray one above rear valve cover) after I took the intake off. I tried testing the wires with the intake off, but I don't get the same values. I might try putting the intake back on and testing it at that connector first. From what I see on this wiring diagram from the library's website, the only possibility that this wire can be shorted to ground is through the RFI. Judging from the wiring diagram, the RFI comes near this DB wire a couple of times, so I'll just have to figure out where now...

 

[TimboSHO]

Alright, I give up. I cannot figure it out. I tried excluding this wire from the circuit and running a new one, and still nothing. No spark no matter what I try. I'm just wondering if something might have happened when I ran the first jumper wire to the coil pack main power and ran it a couple of minutes? It was a fused jumper in case anything went bad. After it shut off then, I haven't been able to restart it no matter what I try. I've been through the flow chart numerous times, I've replaced the DIS and coil pack with working ones and I'm just exhausted and frustrated. I really don't know where to go from here. I'm going to recommend the owner to a shop where I know there's a wiring genius that can hopefully figure it out.

 

[93rev2sev]

Will you let us know what it was?

 

[TimboSHO]

I sure will when I find out!

 

[customperforman]

I too am fighting this very same thing. I now have codes 116 and 636.

 

[TimboSHO]

Bringing this back from the dead with an update

The guy took it to 2 different shops that put over 50 hours of diagnostic time into it without figuring it out (and had to replace the starter from so much cranking!). The last shop it was at hacked the wiring harness pretty good, and actually hard wired the crank sensor in, and had it hitting the vanes. There were soooo many missing pieces and incorrectly installed stuff that it was quite overwhelming. I gave him $500 for the car and brought it to my work. Then I bought a running parts car. I took the complete wiring harness, crank sensor (they were out at the local parts store), D4UI, CCRM, DIS, coil pack (and everything else that was missing/broken) from the parts car and put it in. Try to fire it, still nothing. Now I'm REALLY frustrated. Go over the flow chart that I had and found that the DIS was bad! Somehow, it had gone bad from me taking it off of the other car and putting it on this one. Yikes. So it fired up today! First time in about 10 months. Boy did that make my day! But, it backfires. So i have to make sure the timing is on (I haven't taken the belt off, but I bet the hack jobs that worked on it last did....). Hopefully the timing is off a touch and this car will be on the road soon!

 

[TimboSHO]

UPDATE again. Maybe no one cares, but I'm just happy to have this thing going. The previous shop had #5 and #6 plug wires switched on the coil, and then it ran well, for awhile. Then it started running rough the next 2 starts, and finally didn't start again. Went through the whole diagnostic procedure again and found the crank sensor to be bad (that's what I get for putting a used one in ). New crank sensor in and it's good to go. I've never had a crank sensor make the car run rough before, but that was definitely it on this one. Very odd. I'm just glad I never gave up. It's a really nice car

 

[techi14]

UPDATE again. Maybe no one cares, but I'm just happy to have this thing going. The previous shop had #5 and #6 plug wires switched on the coil, and then it ran well, for awhile. Then it started running rough the next 2 starts, and finally didn't start again. Went through the whole diagnostic procedure again and found the crank sensor to be bad (that's what I get for putting a used one in ). New crank sensor in and it's good to go. I've never had a crank sensor make the car run rough before, but that was definitely it on this one. Very odd. I'm just glad I never gave up. It's a really nice car

Its nice when it pays off aint it! :sun:

 

[93rev2sev]

Step #1 when you buy a SHO:

Timing belt and crank sensor. Period.

 

[TimboSHO]

Step #1 when you buy a SHO:

Timing belt and crank sensor. Period.

The problem is, I put a crank sensor in it first for the P.O. Then the shop hacked it up. So I have no way of knowing if the crank sensor I got was bad, or if there were other problems too. All I know is when I bought it, it needed a wiring harness and crank sensor before I would be sure of anything. I'm just glad it's over. On to the next project....