Truck cranks but won't start and no bus on odometer

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#1
Make
Dodge
Model
Ram 1500
Year
1999
Miles
243000
Engine
5.9L V8
I've got a 99 ram 1500 with 5.9L engine. A few weeks ago as I was backing out of the driveway, the truck stalled out and wouldn't restart. Checked fuel pump and it wasn't running anymore and the no bus and no link error messages began. Also, if I leave the battery connected overnight, it's drained by the next morning. Did voltage drain test and when I pulled the engine control fuse, the voltage drop stopped but after that I'm lost. I don't know where to go next to find my problem. Any suggestions?
 
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#2
If you have a scanner lets see what is stored in PCM

If not no buss often indicates a sensor is pulling down the system.
unplugging sensors 1x 1 may have 'no buss' message go out and we can proceed.
1St is SRS airbag light on?
Unplug TPS, Map, CKP, CMP one at a time and advise.

Do not suspect fuel pump at this time.
 
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#3
Fuel pump was suspected and has been replaced but it still didn't fix the problem. I do have a scanner however it says no link. Tried unplugging each sensor to no avail.
 
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#6
Only way to test a fuel pump is with a fuel pressure tester, had to buy one back in 1985 and have using it ever since..
Some GM vehicles would not start if the pressure dropped from 55 to 50psi, but not familiar with a Dodge.

Have to find the fuel pump relay, on this new stuff, easy has an under the hood fuse-relay box, under the cover says fuel pump relay, pull it, identify the contacts, and use a jumper wire. Does have a hose drain, easiest to pump out water in the fuel tank that seems to be more common today.

Got water in my motorhome tank, stalled 200 miles from home at 1:00 AM in the morning, my wife had her yogi mat, just needed a flash light and a screwdriver to release the output of a fuel filter. Thank goodness I add an electric fuel pump to this thing, told my wife to switch it on, and pumped until two gallons came out, settles on the bottom of the tank. Hooked it up and started just find, but a fuel pump tester would have been so much nicer.

Least having a motorhome, had dry cloths and could wash up. We made it home fine.

One of the biggest jokes a vehicle won't start is the gas tank is empty, common on vehicles when the fuel sender doesn't work. Use to make these out of nichrome wire, but now using strip of carbon on a ceramic substrate, another been counter thing, knocks the price down to about 15 cents with a cheap brass wiper.

Us old guys say they don't make them like they use to.

Your vehicle is 20 years old, do you know since OBD II storing code in flashram, its a micron sized FET that is suppose to store electrons in the gate for a logical zero or none for a logical zero, you have several millions on these, and according to statistics, only can hold their memory up to ten years. If you just lost a couple of bits, your vehicle won't start. One reason with this kind of BS in our vehicles, carrying towing insurance.


Should advertise, if you want problems we have them, friends 2004 VW died, I couldn't do anything with his ECM, for one thing, completely sealed, don't use screws anymore, had to lay out 1300 bucks for a new one, these are produced in the 35 buck range, but some have to make a little profit. I am retired now.
 

grcauto

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#7
Parasitic draw and now the bus is down.....you eliminated sensors but the module itself may be the culprit or the bus pair itself may have a problem.
I have the wiring diagrams and flow charts for this vehicle. Let me know what you want to see.
 
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#8
I did determine that there is a parasitic drain. I believe it's coming from the engine control fuse in the PDC. It's a red/white wire going to a few different places that I'll need to check.
Can anyone point me in the right direction to figuring out why my asd and fuel pump replays aren't kicking on with the key unless we use a jumper wire between 30 & 87?
 

billr

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#9
The "right direction" has already been pointed out. No OBD com from the PCM and the PCM draining the battery sure indicate some kind of problem with the PCM or its connections. The fuel pump/relay is controlled by the PCM and doesn't have a chance of working properly unless the PCM functions are OK; which they obviously are not. Ignore the FP until the PCM issues are resolved.

I suggest taking the PCM out for bench-testing. Connect only ground and power to it and see what voltages you get at the 5V pin(s) and FP pin when you connect the "key-on" power to the PCM. Do you have pin-outs for the PCM connectors, or do you need that from us?
 
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#10
reply #1 asked if airbag light was on ? along with that Horn, and cruise control OK?

Start at the TPS - easy to get to what is voltage on terminals 1&2?
 

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#11
Kev2 said...
no buss often indicates a sensor is pulling down the system.
unplugging sensors 1x 1 may have 'no buss' message go out and we can proceed.
1St is SRS airbag light on?
Unplug TPS, Map, CKP, CMP one at a time
 

grcauto

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#12
I did determine that there is a parasitic drain. I believe it's coming from the engine control fuse in the PDC. It's a red/white wire going to a few different places that I'll need to check.
Can anyone point me in the right direction to figuring out why my asd and fuel pump replays aren't kicking on with the key unless we use a jumper wire between 30 & 87?
As stated above.....the PCM needs to be functioning correctly for the key to work the relay. The PCM controls it.
If you unplugged the different sensors and still the bus is down.....First thing is to check the power and grounds to the PCM.
 

nickb2

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#13
Late in game, folks will hopefully correct me as I write nonsense.

PDC seems to be culprit on BUS/CAN? yes?

Have you tried flipping the PDC and actually unhooking every connector? And looking for corrosion, These are notorious, and I cant say that enough.

I find that if corrosion is found, but no actual pcb damage and pin some what intact. CLR is great. ;):bat:
 

nickb2

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#14
If not, repairing a pdc PCB is not time worthy:money: and a major pain in the arse to do that on shop time, better to call a new or used pdc. No programming needed if powertrain and chassis option vin is followed.
 

nickb2

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#15
Oh, and some oem pdc pin, they are not common ones on the bus/can line. PDC connector repair kits are discontinued up here, we have to make are own now. Not support. But the pdc's they are opver stock, we see at least two a week. Or should I say, I see 2 a week at least.