Had the Computer on my '97 Dakota go out a couple months after I bought it. 200k on the truck. It's a 3.9, manual trans.
Here's what I've done in order from beginning to end:
Checked for spark, none at plugs, no current to coil.
Replaced cap and rotor since they were due anyway.
Checked wires, they were good.
Checked with diagnostic tool, it wouldn't connect.
Replaced shorted out IOD fuse.
Looked for and was unable to find any shorts.
Ran self diagnostic got a 920,921 and 950 code.
Replaced the ECU.
Good spark, starts and runs but very little power and backfires through exhaust sounds a lot like an old truck with the firing order mixed up.
Ran it for 1/2 hour or more and tried to drive it around the property, lots of stalling involved.
Cleaned IAC, no change.
Ran self diagnostic again (several times.) only code showing up is the 950. (ABS.)
Checked and re-checked proper firing order.
Removed connection to each fuel injector and noted a difference in the way the truck was running.
Found and fixed a vacuum leak going to the vapor canister (correct name?) under the truck.
Gapped plugs.
Re, re,re,re,rechecked firing order.

Here's my guesses: The timing chain was making noise, Could be the old computer had adjusted to it being out of spec and the new one hasn't or maybe it jumped a tooth.
Or, it needs the crankshaft sensor replaced. That guess seems a little iffy. Too much coincidence the crankshaft sensor going out same time the computer does and I would think it would throw a code.
I'm about to replace the timing chain since I know it needs to be done soon anyway. I figure that's not just throwing parts at it.
Any ideas would help.

 

Hi Skipper,

Welcome to the forum.

Those are instrument cluster codes, not P-codes, that you are showing. How are you obtaining them?

Have you tried:

Starting with the key OFF, turn it to RUN (not on), OFF, RUN, OFF, then leave ON. Codes should display in the odometer window.

 

Tried that and it didn't work. Held the odometer reset button down and turned the key to the on position. Codes showed up in the odometer window. With the new computer it at least starts and runs. I found the following here: http://www. dodge talk .com/forums/s...ad.php?t=63590


920 The cluster is not receiving a vehicle speed message from the PCM.
1. Check the PCM software level and reflash if required.

2. Use a DRB scan tool to verify that the vehicle speed message is being sent by the PCM.

921 The cluster is not receiving a distance pulse message from the PCM.
1. Check the PCM software level and reflash if required.

2. Use a DRB scan tool to verify that the distance pulse message is being sent by the PCM.

 

If the "key dance" doesn't work, and it may not in '97, then you'll need a scan tool.

The instrument cluster codes you're seeing aren't going to be of much (any) help. That's why it keeps saying "DRB." The DRB is Chrysler's diagnostic system.

 

Well, the new computer got the truck to run but it's running really rough now. Before the computer it wasn't running at all.
I just got the timing chain pulled off. Tons of slop, looked like it had been slapping the side of the cover a bit and you could see the indentations of the old chain in the gears. Doesn't look like it slipped though. I'll put it back together when I get home from work tomorrow and see if that fixes it.

 

Fixed the timing chain. Verified that it hadn't slipped a gear by setting #1 at TDC and looking at the position of the rotor, the timing marks did align as well. She's all back together but still running like crap. Checked the plugs and wires and firing order again.
Now I'm looking at the crank position sensor.

 

Checked the crank position sensor and it was fine, also checked compression, it checked out. Resistance on every wire I could think of, no shorts. So I took the new computer back and ordered one from a different store. Put it in tonight and it runs great. No issues, no backfiring, nothing. Guess the first one I got was programmed wrong or something. Damned electrical crap! This one had me really scratching my head. When everything is right mechanically and some software or electrical problem keeps a rig from running it drives me nuts. Oh well, now I'm back to work on my old ******. Now that I understand.

 

Good news!