I just installed a brand new ECU (computer) on my '97 cherokee sport this morning and it's up and running again and purring like a kitten. However, I have no gauges whatsoever. I have lights etc. and dash indicator lights when first turning the key and an extremely tiny amount of movement on my oil pressure gauge but nothing else. So where do I start?

 

What are the part numbers on the old and new ECUs

 

good question! where exactly would i find those? are they on the barcode label?
Note: there were no guages before i replaced the ecu either. i thought it would reset everything. heheh

 

You should see P56041 followed by 3 larger printed digits.

 

this is whats on the old ECU barcode label
GKQ0R0QF
P56041
T3256
then off to the side in large lettering... 277AC
below that in small lettering... JBSAB
pick an choose. hehe
The techs said they programmed and flashed it for my make and model before they sent it. Was ordered online by my dad from flagship.com
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new ECU only has one number like your looking for:
56041277AD

 

Will the cluster do a function check.

 

That was soooo cool!!
Yep, it does the test and all gauges move and the lights light up. Which is so cool because it has a "cruise" light next to the "low washer" indicator. I don't even know if this thing has cruise control, i've never seen the option.

 

Do you have an obd2 reader? Does it connect to the ecu?

 

Reader: No Plgin Port: yes under dash

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To me this is a cascade failure, I'm just not sure in what direction. Maybe if I tell you how it got to this point you can find the group and location and set out a path for me.

1. Rear Speakers - hit a bump speakers go out, hit another they come on. (short in system but where)
2. Water on passenger floor board - a lil' at first then grew. At one time after a heavy rain a lil' over an 1" of water. Believed it to be a leaking windshield turned out the trench, between the firewall and the rear of the fender well was filled with debri.(didn't even know it had a trench.) water was going into through some vent or hole in the firewall.
3. Rear Speakers Blown - don't know how unless I just never noticed it. Could be because it was a used car when we got it.
4. Rear Windshield Wiper Disabled. Not sure when that happened.
5. Front speakers blown - again same as rear.
6. Radio went out.
7. Side mirror controls disabled - not sure when that happened, possibly because of the leak.
8. Horn goes of by itself at odd hours - It's preferred time was 2am -3am, however it went off at noon one day so I could find the fuse in the inside panel and pull it.
9. Battery being drained - battery was being drained (most likely by the short) every morning. A neighbor looking it up online said there were too many wire groundings on a jeep for removing the negative cable from the battery and that in order for it to stay charged I needed to remove the positive cable until I could find the short. This has worked for a long time.
10. Car turns over but will not run - after reading multiple forum posts replaced ignition coil and CPS then started and ran no problem.

Jumping forward a bit...

11. Light switch falls out - went to store and when I went to turn off lights the switch fell out of the hole within the dashboard. It has to manuvered into place to turn lights on and braced against the back to turn them off.
12. Right turn signal - the right turn signal began flashing faster the left or hazard signals. Someone suggested a bad bulb, but how do you really know with all the electrical breakdowns.
13. Gauges go out while driving - driving home in the rain one day had headlights on, wipers on and used right turn signal. after making the turn looked down to check speed and no gauges no nothing. pulled off to make sure lights were still working. Check. lights still on. Turned on my left turn signal to get home and all gauges came back on.
14. Turns over but will not run - came back from store about a week ago, turned lights off and parked it. Next day got really cold. The following day jumped in to go to appt. an clickity-click-click-click. Figured bad battery connection, readjusted and turns over but won't run. Tested battery and was fine 75% charged (more than enough) So we checked all fuses, fine.
15. Replaced ignition coil - because no fire. But would not even turn over once this was done.
16. Plugged in reader - friend of a friend stopped by and had small reader and plugged it in. It gave a P1964 code. After further study into that online, replaced CPS again.(good call because wiring cover and housing was burned through. But still no turning over.

And for some reason the chorus for "So You Had A Bad Day" keeps playing over and over in my head...

After everyone left I replaced new ignition coil with old, thinking new one was faulty and bam! back to turning over but not running.(YEAH!) The conclusion was I needed a new ECU. Ordered it, got on Monday, installed it on Tuesday and she cranked right up and purrs like a kitten, but no gauges. Re-Checked fuses in both boxes again to see if any were blown. Replaced one inside and noticed a small one under the hood sparked when being pulled in and out.(didn't think much of it at the time) Tried again still no gauges. Did preventative maint. check, fluids, lights etc. all good and test drove it in driveway to make sure it would go forwards and backwards. And here we are! After talking with my dad about the fuse sparking, he told me how to test it, but after having moved it in our rough driveway it no longer sparked. So I know it's electrical, I'm just not sure if it's one thing or multiple.

I found this layout at fuse-box.info. I'm not sure what the difference is between an XJ and the Sport models but the fuse boxes seem the same. The fuse that was sparking was #16. It mentions instrument cluster and radio. If that helps.

Oh and thank you very much for your help! I'm a caregiver so I have to fix the car myself and keep it running. Again thanks.

 

Now I'm really confused! How do you check for power and good grounding on switches and things under the dash when the book says you need to disable the airbag system before working on anything that might set it off, especially when disabling the airbag system means disconnecting the negative battery cable?

I'm currently tracing down the power and grounds for the rear wiper, but according to the only diagram I found online says that there should be a hot wire going directly from the battery to the wiper motor. When i tested for power, i only found one prong that had power and that was only if the switch was on.

Do I disable airbags to check things further or not?

 

Try putting the old ECM back in. I'm thinking the new one isn't programmed correctly, and the ECM was likely never the issue. When multiple systems fail that don't share the same power, it's often bad grounding. Start by removing and cleaning all of the ground wires that bolt to the block by the dipstick tube. Adding a new ground from the battery to the body is a good idea. I also suspect you have a short inside the steering column clockspring which would explain the horn and possibly the CPS/no-gauges issues. Find the connector for that the bottom of the steering column an disconnect it.