90 Wagoneer - no start after ground/electrical refresh

1990 Jeep Wagoneer XJ / 4.0

Recently purchased a 90 Wagoneer that had been neglected by the PO. Drove home ok (~3hr drive) known issues were no AC, brakes/suspension (not dealt with yet),and botched master window switch.

So far this weekend I've done:

**Entire replacement of heater hose/rad/ac system and all lines
- is holding vacuum nicely and no leaks, etc.

**Entire ground refresh w/ beefier grounds, all terminals replaced as needed and cleaned
- thought this was initial problem, re-checked and all testing fine and doesn't seem to be the issue

**New cap/rotor

**New Bosch plugs

** New plug wires

**Valve cover gasket
- 2hrs of scraping the old cork off - clearly hadn't been changed in at least 100k

** New thermostat / water outlet

**New Ignition coil
- testing within spec and fine on multimeter
- ICM was very crusty and was cleaned, is also getting power

**New starter relay
- same as coil

**Vacuum line replacement all around, with exception of replacement cannister


There's more but it really doesn't matter much to the issue at hand.

CPS is testing within spec, tested in AC

Coil, ICM, everything it seems is getting power. Fuel is not the issue, o2 senors are fine, fuel ballast bypassed.

Only thing that should be done, but isn't (first RENIX but not my first rodeo) is I forgot to put the coolant sensor in the new rad, but it is connected and getting power - just don't feel like dumping coolant right now.


Jeep cranks but it just won't start. Next step on my list is going through the pin out on the ECU.

Lastly, there is one "extra" connector on the pass side harness that cannot be figured out for the life of me. 2 pin, blueish connector, red/black wire.


...any suggestions?

Do you have spark? Unfortunately, it's not that unusual for new parts to be bad out of the box, so maybe try swapping the oil cap/rotor back in.

Sorry - no spark whatsoever.

I’m familiar with the broken parts out of the box...have swapped out old plugs, wires, etc.

Well - good news is spark happened.

Believe it's the connection tabs on the ICM to the coil. Luckily there's a 24hr parts store with one in stock.

CRUISER'S MOSTLY RENIX TIPS
RENIX ICU/COIL CONTACT REFRESHING
OCTOBER 30, 2015 SALAD 20 COMMENTS
Coil ICM connectors

The contacts between the coil and the ICU on your Renix Jeep can become corroded and loose causing a complete or intermittent no-start condition. I recommend the following procedure as a maintenance precaution to insure this is eliminated as a possible cause now and in the future.

Coil ICM 2-001

The coil is attached to the ICU by two T20 Torx bolts. Remove these two bolts and lift the coil up off the ICU. You will see 2 pins and 2 sets of contacts. Clean both the pins and springy contact pieces with a good electronics cleaner and some fine sandpaper.

Squeeze the springy contacts closer together with some needle nose pliers. Apply some OxGard to the contacts. Bolt the coil back on to the ICU.

While you’re right there, unplug the connectors from the ICU and inspect the pins in the harness connector. Make sure the pins are not retracted into the connector. Spray out the connector and the receptacle of the ICU with the same good electronics cleaner you used earlier.

I feel this procedure should be performed at least once in the lifetime of a Renix Jeep.

cruiser54 said:

CRUISER'S MOSTLY RENIX TIPS
RENIX ICU/COIL CONTACT REFRESHING
OCTOBER 30, 2015 SALAD 20 COMMENTS
Coil ICM connectors

The contacts between the coil and the ICU on your Renix Jeep can become corroded and loose causing a complete or intermittent no-start condition. I recommend the following procedure as a maintenance precaution to insure this is eliminated as a possible cause now and in the future.

Coil ICM 2-001

The coil is attached to the ICU by two T20 Torx bolts. Remove these two bolts and lift the coil up off the ICU. You will see 2 pins and 2 sets of contacts. Clean both the pins and springy contact pieces with a good electronics cleaner and some fine sandpaper.

Squeeze the springy contacts closer together with some needle nose pliers. Apply some OxGard to the contacts. Bolt the coil back on to the ICU.

While you’re right there, unplug the connectors from the ICU and inspect the pins in the harness connector. Make sure the pins are not retracted into the connector. Spray out the connector and the receptacle of the ICU with the same good electronics cleaner you used earlier.

I feel this procedure should be performed at least once in the lifetime of a Renix Jeep.

Click to expand...

Thanks - yes all that was done and the entire engine bay way cleaned and a cost of rust prevention was done before anything was put back into the bay.

The specific issue I was having was solved - while the ICM/ICU tested fine the connectors between the ICM and the coil were corroded underneath what was visible - new ICM and it started right up.