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Stock XJ Cherokee Tech. All XJ Non-modified/stock questions go hereXJ (84-01)
All OEM related XJ specific tech. Examples, no start, general maintenance or anything that's stock.
Pin B10 at the ECU is power from the latch relay and A9 is ground from that relay.
I have battery voltage at pin B10, which means the relay is working. When I checked A9 for ground it was in the M ohms range with a decreasing value. I assume this means that it is going through some capacitors inside the computer. I disconnected the A/B Connector and there was no connection ground. Just out of curiosity I put a jumper wire from D2 Pin 3 (same ground) to a good ground. all it did was engage the relay and I still have a no spark condition. So I think that the A9 ground is working properly just has a strange reading when the ground is provided.
Second note, before I removed my distributor (weeks ago) I put a mark on the head where the rotor was pointing, so I wouldn't have to set the engine at TDC. My old sync sensor was not functioning at all so it never mattered where #1 cylinder wire was connected on the cap. Because I didn't really understand what the sync sensor was doing and partially because I didn't think about it, I just put the new one in the same as the old one came out.
Last night I put the engine at TDC for the #1 cylinder and installed the distributor where the rotor was pointing where the #1 was marked on the distributor cap. I had high hopes for a running engine but still did not get one.
Last edited by Cjjcalhoun; 07-11-2017 at 11:07 AM.
I have battery voltage at pin B10, which means the relay is working. When I checked A9 for ground it was in the M ohms range with a decreasing value. I assume this means that it is going through some capacitors inside the computer. I disconnected the A/B Connector and there was no connection ground. Just out of curiosity I put a jumper wire from D2 Pin 3 (same ground) to a good ground. all it did was engage the relay and I still have a no spark condition. So I think that the A9 ground is working properly just has a strange reading when the ground is provided.
Second note, before I removed my distributor (weeks ago) I put a mark on the head where the rotor was pointing, so I wouldn't have to set the engine at TDC. My old sync sensor was not functioning at all so it never mattered where #1 cylinder wire was connected on the cap. Because I didn't really understand what the sync sensor was doing and partially because I didn't think about it, I just put the new one in the same as the old one came out.
Last night I put the engine at TDC for the #1 cylinder and installed the distributor where the rotor was pointing where the #1 was marked on the distributor cap. I had high hopes for a running engine but still did not get one.
First off, the sync sensor has NOTHING to do with ignition or timing.
OP: See page 20 of the Renix Fuel Injection manual. It describes what the sync pulse generator does. Basically tells ECU when to open injectors in combination with crank sensor...
I've been pretty busy and extremely unmotivated so I haven't attempted anything in a while. Maybe next week I will come up with something new to try but for now there isn't anything I want to try....again.
I got out there tonight and had spark, for a few minutes but still no crank. After the five or so minutes the spark went away. I started looking at the injector signals while it had spark and I got no voltage at the injector #1 connector when The engine was cranking. The ground from the injector connector was at 1 ohm.
I investigated the signal called injector feed. When the key is turned on I get 12V at the D1pin 6. The 12v stays until the fuel pump builds pressure and then it goes away (about three seconds). With the key turned on I have about 50 ohms and with the key turned off it is about 1-2 ohms to ground. Is this a normal reading? I can't imagine a voltage carrying signal being shorted to ground being normal. I disconnected a few components (fuel pump relay, O2 heater relay, O2 sensor, AC Clutch, EGR selinoid and the ECU) and the ground remained. I have yet to crawl under to disconnect the fuel tank unit(?).
On my schematic there is a point where this signal splits to go to all of the different components. Does anyone know where that is located on the jeep?
Thanks Cruiser but I believe I have those already. You posted them earlier in the thread. The diagnostic connector pin out has been extremely helpful throughout this process.
I can always hand over hand the orange wire but there is a lot of wire loom and tape so I would be looking at a significant amount of time trying to find the short. If I can find the junction I can reduce that time.
07-09-2017, 01:20 PM
