I am working on a 1999 S210P that is exhibiting a crank no start. The issue started intermittently where we would would not hear the fuel pump relay clicking but then if it sat a while it would energize the relay and want to start, now I can't get the truck to start at all. We can confirm the EFI and fuel pump relays are getting 12v at both their low current trigger wires but never see ground, when the issue was intermittent we would see ground for the 3 seconds at the fuel pump and ground at the EFI Main relay. I feel like I am missing a ground to the EFI Main but I can't find where it is supposed to be. I believe the fuel pump relay gets its ground from the ECU but I am under the impression that the EFI main doesn't. The EFI relay has a light green and white w/ black stripe for trigger wires, both show 12v at all times once the key is turned on. On the fuel pump relay I have a light green and black w/ white strip which both show 12v once the key is on. I even purchased the S210P electrical manual for the truck and it doesn't seem to be 100% accurate, it doesn't list any light green wires at the relays, it shows one of the white w/ black wires going to a Xf connector somewhere near the steering column but no white w/ black wire has 12v in that area while the white w/ black wire has 12v. Kinda lost here, I feel like the ECU is the culprit but the EFI relay should be getting ground external to the ECU according to the wiring.
Have you been able to identify any ground wires? Is there good continuity between engine and frame of truck?
SOLVED!!! I noticed I was reading the electrical diagram book wrong and that the Xf connection was a junction to another wire, once we found that the connections are plastic multi junction and not single rings I was able to identify all the ground points and one all the way in the back by the fuel filler that was filled with dirt and had a spade connector broken, with that cleaned and repaired the fuel pump kicked on with the key and the truck fired up.
