- This topic has 54 replies, 5 voices, and was last updated 8 years, 8 months ago by
.
-
Topic
-
Hopefully someone more experienced in the electrical side of things can chime in on this one.
My mom just bought a 96 ram 1500 with the 5.2, it wasn’t running when she bought it, but it was a clean truck, and for what the truck has and what she paid for it, it was a good deal to jump on.
Anyhow, the guy she bought it from said he thought the crank position sensor was the issue, ok $70 bucks, worth a shot. well I turned the key to the ON position and listened for the fuel pump to prime and it didn’t, checked for pressure at the rail and there was none. so I checked the 20A fuse under the hood for the fuel pump and sure enough it was blown. so I swapped it with a slightly higher amperage fuse just to test it and the fuel pump primed and the truck fired up, then shut down. now when you turn the key to the ON position, the fuel pump just keeps running, and the relays in the underhood block click like crazy until you turn the key off. and it won’t start back up. anyone have any ideas? I’m leaning towards a short in the circuit, or a bad ECM possibly, but before I start really getting into this thing I wanted to get some suggestions. thanks in advance.
-
Replies
-
right on, thank you. I’ve found a few wiring diagrams online, but they’re all contradicting of each other as to color coding or which terminal does what exactly. I did see the black/DG wire down in the fuel pump harness today though. I’m gonna put some time in on it tomorrow and see if I can get a little further with it. and yeah, I think I’ve learned my lesson on the higher amperage fuses, I don’t really feel like going to the jungle gym that is my local parts yard after an ecm again anytime soon, I think I cleared them out of all the ones that might work for this truck as it is lol
well, so far no dice. unplugged the fuel pump back at the tank, still pops the fuse. Unplugged the ignition coil, still pops the fuse, pulled every bit of aftermarket wiring out of it, and still pops the fuse. every bit of wiring I’ve touched has been in good shape.
2 things I have figured out though, if the grey plug bundle on the driver side of the firewall is unplugged, it doesn’t pop the fuse, and if the #9 fuse in the interior fuse block labled ”ENG” is out, it doesn’t pop the fuse. does that help any?ok, dropped the fuel tank and inspected all the wiring from the pump to the distribution block, all looks good.
behind the driver front wheel, under the inner liner, theres 2 plugs that come off the harness out of the engine bay, one goes back to the fuel pump, one looks to go up to the firewall or into the cab. I unplugged both of those and checked if it blew the fuse and it does. so its not the wiring back to the fuel pump.. I’m thinking its something in the cab, maybe a bad ignition switch?
I pulled the ignition switch out because the previous owner said he replaced it, and the plug that goes onto the switch looks like it had caught fire before because it was all melted and beat. and all the wires were extended with about 20 butt connectors.. however, even with everything unhooked and no wires touch each other, it still blows the fuse, so I don’t think that’s the source of the problem either.
it may be whatever overheated/damaged the ignition plug may have damaged something else near by. i would inspect all of the wiring near that connector very carefully. also look at the plug that goes into the cab by the fender well that connector may have overheated and may have damage inside it that is not readily apparent.
the connectors by the inner fender well, are both outside the cab and they both looked good inside and out. if I get any deeper into the wiring inside the cab I’m gonna have to pull at least the top half of the dash out and get into it. I’m thinking about pulling the ignition switch apart and see if theres anything in it that doesn’t look right.
I need to look up all the recalls on this thing, but unfortunately I doubt the dealership would even touch this thing to honor a recall with everything that’s been done to it.
I have the recall up on another screen, but there’s too much I just won’t be able to post in the thread. Here’s the recall number instead. I’ll also include enough to tell you whether or not your truck is included in the recall.
RC-875-00: SAFETY RECALL #875 — IGNITION SWITCH WIRING (JUNE 2000)
1994-1996 (BR) Dodge Ram Trucks
NOTE: This recall applies only to the above vehicles built at the:
•Warren Assembly Plant (“S” in the 11 th VIN position) through April 4, 1996 (MDH 0404XX);
•St. Louis North Assembly Plant (“J” in the 11 th VIN position) through March 23, 1996 (MDH 0323XX);
•Lago Alberto Assembly Plant (“M” in the 11 th VIN position) through April 14, 1996 (MDH 0414XX); or
•Saltillo Assembly Plant (“G” in the 11 th VIN position) through April 14, 1996 (MDH 0414XX).Google this: RC-875-00
That might get you the whole body of information included in the recall.
actually, that reminds me. I noticed whenever i’d turn the key ON, it would click the AC clutch, even with everything on the HVAC controls turned off. think that might be related? cause it seems the recall pertains to a relationship between the HVAC and ignition switch.
The recall said something to the effect of the blower motor operation would overheat the ignition switch. There’s a relay bypass install that also goes along with the repair for the blower motor to isolate it from the ignition switch. The compressor engagement does not apply to the recall. It is, unfortunately, another symptom to deal with.
I haven’t forgotten about studying those diagrams either. I found the OE’s and they’re worse than the Mitchell diagrams. In the meantime, this is straight out of the Description and Operation pages of the manual:
[b][size=4]The ASD supplies battery voltage to the fuel pump, fuel injector, ignition coil, generator field winding and oxygen (O2S) sensor heating element. The ground circuit for the coil in the ASD relay is controlled by the powertrain control module (PCM) The PCM operates the relay by switching the ground circuit on and off.
The fuel pump relay is controlled by the PCM through same circuit that the ASD relay is controlled.[/size][/b]
I’d suggest you try disconnecting everything listed in that description/operation segment as part of the short diagnosis for now.
I’m starting to wonder if you’ve got a corrosion problem in the fuse block. I just happened to diagnose a fuse block today that was shorting out the driver’s side head light circuit so maybe I’m just guilty of wishful thinking here. Just the same, it’s worth sharing my situation. The fuse for the left side headlights was blown, but I was still getting roughly four volts going to them. I found corrosion all over the bottom of the fuse block and it was conducting transient voltage. Believe it or not, I was able to separate the core fuse grid out of the block housing and I dunked it in baking soda and water for about ten minutes. I took my sweet time drying it out as well as I could with a blow gun and I cured that short to the headlights.
Once again, it may be wishful thinking on my part, but I know that Dodge minivans forever had corrosion problems with their fuse blocks too. It might be a “genetic condition” so to speak.
I haven’t messed with the wiring to the injectors or alternator yet as far as eliminating them from the circuit, the o2 sensor was broken so I just unplugged it from the harness (didn’t help or hurt anything)…..actually, come to think of it. if the ASD goes directly to the injectors, that would mean a faulty injector wiring or harness could be the problem right? my brother mentioned today about seeing what looked to be an ex-rats nest or squirrel nest on the passenger side upper intake area right by the injector wiring. I’ll take a look at that tomorrow after work and see if it helps anything. in the meantime, theres no fuses for anything in the interior in the vehicle right now.. I eliminated EVERYTHING inside the truck as part of my investigation..
Remember that you’d still need to find a correlation between the injector harness and the fuel pump power wire. The injectors are ground side switched and it’s the PCM that does the grounding only when there’s a crank signal. So I’m having a tough time saying there would be a problem with an injector wire shorting the fuel pump.
BUT, any time you can find evidence of a rodent chewing up your harness, there’s always potential for a shorted circuit. Do check out the entire area where that nest was at and you might find your short.
no wires chewed in that area.. I can’t think of any other area’s aside from the ignition switch that would tie into that circuit on the power side, and no affect something else on the truck. the ac clutch, and the fuel pump fuse going out are all that I’ve seen. I’ve checked everything else.
do you think, based off the diagrams you have handy, that hotwiring the fuel pump (at least as a investigatory process) would be enough to bypass that fuse and see if the truck will fire up? or do other things rely on that fuse having connection?
I can’t answer that without having the truck in front of me and I don’t want to suggest anything that could ultimately cause more problems. You have so many odd variables and that fuel pump circuit is one of the most suspicious points I’ve been staring down in my diagrams.
Have you given any thought to what I suggested about a short directly inside the fuse block? I’m not saying run and get a new block out of the salvage yard, but do take the time to flip the block and look at connections underneath for corrosion.
I flipped it and checked it out the other day, it was in great shape, no signs of burns, moisture damage, corrosion.. unless there’s an issue inside the fuse block in the driver side of the dash, that ones a little trickier to get out. but if I can’t find anything under the hood, that’s gonna be my next stop.
I think I’m on the right path to tracking it down with what does and doesn’t affect it.
so far, the list goes:
ASD relay
grey plug on the driver side of the firewall (the middle of the 3 main ties to the engine harness, theres black white and grey)
fuse #9 labled ENG inside the truck in the interior fuse panel
and ECU, if any of these are disconnected it doesn’t blow the fuse.everything else I’ve tried, if those are hooked up, the fuse inevitably becomes a sacrificial part. as soon as the key touches the ON position.
no_common_sense, do you have a link to where you get your diagrams? I can’t find a full listing for this truck, and without ordering online can’t get a helms manual. and Haynes manual’s are awful for electrical
Fuse 9 is a wash. It supplies power to the ASD relay. Disconnecting the ECU also disables the ASD relay so that’s a wash. Any fuse blocks inside the cabin are probably irrelevant so don’t bother trying to remove it. I was only interested in the under hood block. I don’t know what to say for that grey plug. They do the same thing with the ECU. It likewise gets a black, grey, and white connector to it.
This is where I miss private messaging. I’ve been primarily been using a login to identifix and that’s a login that’s been assigned to me at work. I can’t share that with you. I used to use this link a lot for OE diagram access. It might help you out on future endeavors.
- You must be logged in to reply to this topic.