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'96 rodeo/passport fuel pump not getting volts
05-06-2013, 09:34 PM
Post: #11
RE: '96 rodeo/passport fuel pump not getting volts
Let me answer your last question first. In a word; “Yes,” it would be dangerous to connect a jumper wire for any distance of travel. Once the jumper wire is in place, all of your safety equipment is pretty much disabled. If you were in an accident; even if the key was turned off, the pump would continue to run. So it’s kind of one of those situations of “How much is your life worth?” Are you worth more than the tow bill? How lucky are you? Some people do stupid things all their lives, up into their 80‘s. Others (like me) get zapped the first foolish thing that they try. I know that if I was going to risk that I would at least put my jumper on a source that turns off with the key. That would provide a small amount of safety. But anymore I shy away from those things that “Seem” like I’m saving money. It only takes once to cost you everything. And I’m not an overly lucky person. Before you make a decision, check your auto insurance policy. I had coverage for towing on mine and didn’t even know it. You might too?

Now on to the continuity test. Yes, where the leads are hooked when testing continuity changes everything. I don’t know an easy way to explain this so you’ll have to bear with me. I can set my meter to “Beep” when I have continuity. To test that I just touch the black lead to the red & it beeps to say that there isn’t any resistance. So when you test a wire you place the red lead on one end and the black lead on the other end of the wire. If it is good the meter beeps because it’s just like touching the leads together. No beep means that something is wrong between the two leads. If your meter doesn’t have the “Beep” function you should touch the tow leads together and see what it is reading. It should read the same when you are checking the wires if they are OK.

Another thing is that you can’t allow either end of the wire being tested to be attached to any other component. If one end is bolted to a ground on the body it has to be unbolted. One end can’t be plugged into the ECM. That would need to be unplugged. Now the end that you plug the relay into can stay in the relay box as long as the relay is removed. That end is insulated from the other wires by the plastic box.

I can’t really offer much help without knowing if this test was done correctly. The way that I read it, it doesn’t sound right to me. It sounds as though you didn’t unplug the ECM & didn’t unbolt the ground. I also don’t know if you had the leads in the right place & the meter set correctly. I’ll wait to hear back from you so I don’t confuse things by guessing.

Thanks for using the forum,
Garner

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05-06-2013, 11:34 PM
Post: #12
RE: '96 rodeo/passport fuel pump not getting volts
Just back and my brain is not too sharp tonight but to clarify things I will say that I have zero experience with the vehicle, but many years worth (from 20 years ago) working with that numbering system because that's what Bosch and all of their outside licenses used since the 1960's. Seems VW, Chrysler, Nissan, BMW, and a few others still use it.

That said, what I am seeing is the relay "switching circuit" for your coil is not working. Look at your original diagram again. The coil is the circular part with the slash. One wire needs to be hot and the other needs to have a ground for the other contacts to close on command. Since you say there's no power there I suspect a blown fuse or fuse link that you have not found yet.

If it comes down to it, I like Garner's suggestion of a power feed from the key as your temporary connection. At least you have the option to kill the pump from the driver's seat. As a safety measure you can use a fuse holder (10 amps should do it) and crimp on a couple of lugs then use that as your jumper lead.
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05-07-2013, 10:58 AM
Post: #13
RE: '96 rodeo/passport fuel pump not getting volts
I tested for continuity again and have continuity to ground on coil side of relay and none from relay to PCM (resistance reading of between 4 and 5). Should I check the wire from relay to PCM since i found the resistance measurement of 4 to 5 ohms?
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05-07-2013, 11:33 AM
Post: #14
RE: '96 rodeo/passport fuel pump not getting volts
At this juncture you should check everything that you suspect to be a possible problem. Pulling the plug on the ecm and see if anything changes then make sure it reads "zero" ohms from end to end.

Heading to work right now and will all of my "catching up" I probably will not check in again till later this evening.
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05-07-2013, 04:22 PM
Post: #15
RE: '96 rodeo/passport fuel pump not getting volts
i pulled the plug on the ECM and had the same measurements, 4-5 ohms.
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05-07-2013, 11:03 PM
Post: #16
RE: '96 rodeo/passport fuel pump not getting volts
If you are absolutely sure it's the same wire (same colors and conductor size) then you are onto something. Follow the harness and look for signs of rubbing, heat, and other damage. You can also "probe" the wire a few inches back from the ends (use a sharp object to pierce the insulation) just to be sure it's not a bad connection to the crimp terminals. If you have a meter with a "buzzer" you can try the jiggle test to see if there might be a broken section, which could be an easy fix once you spot the area.
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05-11-2013, 12:15 AM
Post: #17
RE: '96 rodeo/passport fuel pump not getting volts
I have not been able to find the damage to the wire. Would there be a problem if I ran a new wire splicing it at either end?
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05-11-2013, 12:31 AM
Post: #18
RE: '96 rodeo/passport fuel pump not getting volts
That would be an acceptable fix, although you must be absolutely certain it is the right wire or you may do damage. (read: expensive damage)

Good luck and keep us posted!

BTW, if this fixes the problem you should make soldered connections rather than just using crimps. That way you will not have poor connections down the road with moisture, etc.
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05-11-2013, 02:34 PM
Post: #19
RE: '96 rodeo/passport fuel pump not getting volts
Could I strip the wire, not cut it, before the plug & relay and run a temporary wire to test it? I am pretty sure it's the correct wires because the info. in the shop manual has the color of the wire, the position at the relay and the specific position at the PCM plug. As I read the wiring diagram, attached in an earlier post, the wire has no other plug or connector between relay and PCM, therefore I should get a continuity reading of 0? i am a weekend mechanic and I don't have a lot of experience working with electrical stuff. I really appreciate all the time and brain power being used to help me out.
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05-11-2013, 11:13 PM
Post: #20
RE: '96 rodeo/passport fuel pump not getting volts
That's not a bad idea... and to be extra cautious I would put a fuse in that line to protect yourself. Seeing as this is only a trigger circuit use a small fuse. 1-2 amps should cover and smaller is better. I'd guess the normal draw (if all else is well) would be around a quarter amp.

If everything works then route a new wire out of harm's way and secure it in place.
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