Rot Box

Great work, thanks you for the reply. I’m starting to think I’m in over my head haha. Ive been driving it for short periods of time. The only codes at the moment are p1693 and p1694 If I could get the transmission to work I could externally regulate the alternator and solve the charging issue... then again I’d like it to just work the way it was designed to. I don’t know if I’m dealing with a bad ecm, pcm or wiring harness at this point. Oye this is frustrating

Hey everyone. I'm back with the same ol' problem.. The truck hasn't changed too much other than I swapped in a P7100/p-pump because I wanted the simplicity of mechanical injection. To recap. The truck runs fine--GREAT in fact. Then randomly I loose the tach, fuel pump, alternator stops charging, it stays in third gear (I'm able to shift it manually to second but not first) and sometimes I loose the oil pressure gauge. I loose power to the VP44 as well which used to shut the engine off. No codes aside from P1689 which is expected with the pump swap. I've inspected and tested the ecm/pcm grounds as suggested. I have inspected every plug, wire/ wire harness etc that I can find and everything looks just fine. I've completed the W-T mod and checked ac ripple and that comes back good. Everything seems to point towards a bad cam position sensor, but I've changed that already. Swapping back and forth between my old and new one doesn't make a difference... Do I haul it to the stealership or shop and let them work on it? I'm out of ideas and I NEED this truck. Thanks again for any help Edit: I was able to get a few more codes off of my gauge cluster that none of the other scanners/code readers picked up: P1693 P1694 P0230

Thanks guys. Been out on business the last few days.. Dripley, I like the headlights they're just the cheap amazon specials with the stock size bulb however I am running an LMC Truck 'heavy duty headlight harness' which is powers the lights off of relays so they're a fair bit brighter than stock.

Thanks guys. I like them close to stock as well. I don’t see many around here but when I do the tires are wider than they are tall.. bro trucks

Well that was fun. It took some effort but I was able to get it off the road and into a parking lot. I can go start it right now and it’ll run but it randomly shuts off and may or may not restart. I put about 120 miles on it before it started to act up. looks like I have a few codes. I’ll post these here so I don’t forget what they are. P0237 P0112 P0118 P0113 P1698 P1689 P0380 P0382

Bumped up the fuel pressure to a nice 17 with a shim washer. That being said....

Very glad I joined the forum. Lots of great info here thanks everyone for helping out a newbie. I’ll get this pump turned up asap.

Alrighty I put about twenty miles on it and so far so good. I have to admit though I’m pretty nervous.. Fuel pressure gauge is a nice addition. I’m seeing 14psi at idle and 10 at wot.

Well the truck fired to life without issue. I quickly tested the ac ripple and assuming I did it correctly this is what I found... 22.2mV is the highest I’ve seen so far. Oye is this too much you think? Also Jag, when you say paralleling should I run a negative cable from battery to battery?

Just spent the afternoon doing the W-T mod. Seems pretty straight forward.. assuming I did it correctly. -Alternator charge cable now connected to pass battery. -Ground bundle (four black/tan wires + new #6 cable grounded to engine by vp44 and then over to the driver side battery negative. Sound good? Thanks again everyone

Will do. I ordered one from ACS Auto Computer Specialists costumer service has been good so far..

Ok that makes sense thanks again. Took awhile to sort out the mess but I finally have the pump wired up properly and with a good relay. Thinking I’ll pull the trigger on an ecm tomorrow and work on testing out the alternator.

Good to know on the alternators. I’ll read up on and check the ac noise as soon as I can. Hmm I wonder why they would have wired it into the central timer... Is it bad to have the lift pump run constantly with key on? The more I did into this wiring the worse it gets. Whoever wired it made a nice mess of things. I’m thinking I’ll order a new harness from air dog and do it right. Thanks for the help you guys.

Thanks for the help, Yeah the lift pump runs constantly when the key is on. The relay is getting keyed on/off power from this wire tap on the blue/white wire on a box under the dash above throttle petal. Oye who knows haha.. I’m guessing this is not wired correctly. I installed a reman Bosch alternator after the ecm died just to be safe. SIA electronics checked out my ECM. Said the micro processor is fried. Andrew

Jag thanks for the help. The previous owner wired the lift pump (it’s an Air Dog FP-100) so I’m not sure. That said if I turn my key on the lift pump will run constantly even with the ecu removed.. is there a better way to tell? Also I’d like to add a fuel pressure gauge asap. Andrew