Hello all I'm sorry for having to ask for wiring help but I have read many threads but could not find the solution to my problem. I have completed a chassis swap on my '97 Tj and it won't start. It ran before the swap but now there isn't a proper ground at the fuel pump connector.I have 12 volts at the plug and the fuel pump runs with alternate 12v source, all the relays and fuses are good. the Jeep runs on starting fluid.My problem is I can't quite decipher the wiring schematic, I'm trying to trace the ground wire circuit and it looks like the ground wire goes to a S132 connection then to a G105 connection then an S130 connection and on to PCM cavity A32. Am I to assume I should have continuity between all these points with the key on or off? What are the connecting points S132, G105 and S130, are these ground points on the engine block and body? As you can tell wiring is not my strong point. thanks in advance for any help, Gary
Fuel pump wiring / ground
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You should have grounds under each speaker cover, and on the driver's kick panel...then one on the firewall in-between the battery and valve cover running to the battery.
-Mac
-Mac
Thanks I have all those in place and secured. I was trying to deduce whether the fuel pump ground circuit was attached to the block or it went to the ASD relay Or PCM first. I'm not adept at reading the schematic.
Should I have ground continuity at the fuel pump plug with key off and then the ground will cut out after 1.8 seconds after turning key on? Right now I have nothing
Looking at the diagram, the ground signal from the PCM only completes the circuit to the fuel pump relay, not the pump itself. The ground to the fuel pump module itself comes from ground point 105, through splice 132. So you should have continuity from the negative side of the pump connector to ground at all times whether the key is on or off.
If there is no ground continuity at the plug to the pump and ground point 105 is secure at the right rear of the engine block, check splice 132 located in the loom near the back of the bell housing. See pics.
Does the pump run if you bring in a known ground to the negative side?
If there is no ground continuity at the plug to the pump and ground point 105 is secure at the right rear of the engine block, check splice 132 located in the loom near the back of the bell housing. See pics.
Does the pump run if you bring in a known ground to the negative side?
Yes the pump runs if I connect a ground to the frame . There is constant 12 volts at the connector. The ground connections at the block are good. I guess I will have to disassemble the loom.Thanks , Gaty
My guess is the wiring harness got dinged around the transmission during the swap.
Really easy to pinch wires.
-Mac
Really easy to pinch wires.
-Mac
Good point, it doesn't necessarily have to be at the splice, it could be anywhere along that loom.
if I ran a new ground say from the block where the others are attached to the connector wouldn't that defeat the PCM control of the ground wire?
No, look at post #5 again. That ground is not controlled by the PCM, it's constant. The 12 volts should not be constant, it should only have 12 volts at the pump when the key is on and the PCM commands it by grounding the fuel pump relay.
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Technically the closest "ground" to the fuel pump is the tail light wiring.
Something tells me you're going to find more damage that just that ground wire.
My guess is the shop pinched or stretched that harness and the pump ground is just the beginning.
-Mac
Something tells me you're going to find more damage that just that ground wire.
My guess is the shop pinched or stretched that harness and the pump ground is just the beginning.
-Mac
Unfortunately I was the shop so I hope when I tear into it it's just the ground wire. Thanks, Gary
Found the culprit. Must have snagged it during the swap. Thanks everyone for the help. Gary
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