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Discussion Starter #1
Hi folks,

I've got an issue with my 2000 S10 with a 2.2L in it. It drove home just fine on Wednesday night after I filled up the tank. Parked it, tried to start it Thursday morning to head to work, and it would not start. It cranks just fine, but will not fire, no kick, no backfire, nothing.

The fuel pump I replaced with an AC Delco unit 3 years ago. I listened for it to run for the 2 second kick when I roll the key on, I get nothing. So I checked to see if my relay was clicking, and got nothing. I tested the relay, and it tested OK. I swapped out another relay just to be sure (used my horn relay) and still got nothing. Using a volt meter I checked the voltage to the relay using the diagnostic port along side the relay, and got .348 volts continuous when the key is on. No 12 volt for 2 seconds at all, but a continuous .348 volts. I checked the ECM-B fuse, it's fine. Voltage to the fuse was a bit low, but that's because the battery was only at 11.9 volts after a bunch of cranking and testing. So I broke out my OBD-2 scan tool to scan the ECM, and it would not communicate with the ECM. I tried another scan tool, and it too would not communicate. I checked to make sure I had power to the OBD-2 plug, and I do, just no communication from the ECM.

Now, at this point, it's worth pointing out I had an ECM failure on this pickup before, about 8 years ago. 2 of the drivers for the fuel injection went out on the original ECM, and after a noid test I replaced the ECM with a remanufactured ECM from NAPA (over 200 dollars), and the problem was solved.

So at this point, I'm assuming this reman ECU has failed since I can't get any scan tool to communicate with it, but I wanted to ask here before I spend more money, and get some insight from the guys that really know these trucks. It's been a great truck. 302,000 miles and counting, and I haven't had to do much to it! I originally got it with intentions on stuffing a v8 under the hood, but after driving it awhile, I've decided to leave this truck alone and get another truck for a v8 swap.
 

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Sounds like you know what to check and how to diagnose the problem. Might want to consider an JY 2000 2.2 PCM just to see if it is readable with the scanner and provides B+ to the relay.
Unless it's an identical vehicle it would likely need re-programming, but it would tell you if the issues are PCM or wiring.
 

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Pull the relay, the two left relay socket contacts should be ground. The .348v is on the test contact that is located to the lower left of the relay? Does it have that voltage with the relay removed? With the key off? Do all the dash lights come on when the key is on?
 

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Discussion Starter #4
Sounds like you know what to check and how to diagnose the problem. Might want to consider an JY 2000 2.2 PCM just to see if it is readable with the scanner and provides B+ to the relay.
Unless it's an identical vehicle it would likely need re-programming, but it would tell you if the issues are PCM or wiring.
That's not a bad idea. If I can find one I can use I'm going to try that. If not, I may just try an 88 dollar gamble with another reman, this time from Auto Zone. Finding a known-good unit that I can trust might be hard, or convincing someone to loan me theirs for a test. Thanks!
 

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Discussion Starter #5
Pull the relay, the two left relay socket contacts should be ground. The .348v is on the test contact that is located to the lower left of the relay? Does it have that voltage with the relay removed? With the key off? Do all the dash lights come on when the key is on?
Just tested the grounds with the relay removed, using a test light. Both grounds appear good. The .348v is indeed on the test contact just to the left of the relay, the single female pin. Also just tested the voltage at the test contact with the relay removed, and it has .09v with key off, the same .348v or slightly less with key on, and stays constant on both tests. All dash lights come on as normal when key is on. Fuel gauge is not working. After a few seconds all lights turn off except Service Engine, Low Fuel, Battery (which is by now about 11.5 volts because I have yet to put a charger on it) and Seat Belt (including this just in case). After roughly 45 seconds of key-on, the SECURITY light comes on and stays on.
 

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With relay removed, do you see 12V on the lower right socket for 2-3 seconds when key is turned on? Try it with a test light connected to ground. If you use a dvm, you can be fooled by the hold up resistor in the ECM.


Also, do you hear the pump run if you apply 12V to the test contact?
 

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Discussion Starter #7
rimara, I didn't get a chance to do any testing tonight. I will get to it tomorrow after work and post results. Thanks for the help guys!
 

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Discussion Starter #8
With relay removed, do you see 12V on the lower right socket for 2-3 seconds when key is turned on? Try it with a test light connected to ground. If you use a dvm, you can be fooled by the hold up resistor in the ECM.


Also, do you hear the pump run if you apply 12V to the test contact?

Relay removed, no 2-3 second light when key-on at the lower right socket. Constant 12 volt on the upper right. The pump does run when jumped from 12v to the test contact.
 

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The 12V signal from the ECM is not getting to the relay. Possibilities are:
1. ECM is bad and not sending the signal.
2. Wire or contact from ECM to fuse box is shorted or open
3. Fuse box is bad
4. ECM has bad power or ground.


First, check all fuses.



The wire from the ECM is a dark green/white and runs from C2-8 on the black ECM connector to C2-B7 on the fuse box. This is what connects to the lower right relay contact. You can check for short or open by pulling the relay and the black ECM connector, and then with your DVM see if you have continuity between both ends, You can also check to see if the wire is shorted to ground. If you need to, you can look at the contact in the bottom of the fuse block, the connector is the big black connector (C2), contact B7, the green/wht wire. You can also check to see if the 2-3 sec 12v is showing up at the ECM by back probing the C2-8 pin when key is first turned on. You have to do this with ECM connector on since you need power to the ECM during the test. Another test is to see if you see 12V at the ECM1 fuse with key in run. Don't pull the fuse, just probe the pads on top. This is a test to see if power is getting to the ECM from the ignition switch.


You might be able to find a schematic of the fuel pump circuit by looking on google images and searching for S10 fuel pump schematic or something similar.
 

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Discussion Starter #10
I was able to do some testing before I got rained out. The pickup isn't under cover where it's at, so I didn't want the electronics getting wet.

Started off testing power to the ECM1 fuse. Nothing with key-off, full battery with key-on. Tested the fuses, they all have continuity through them. So I don't believe it's the ign. switch at this point. Next I removed the harnesses from the ECM andusing a DVOM tested for continuity to the lower right socket on the fuel pump relay location. I can't see if there are any location markings for those sockets on the plugs, so I probed every location. Only one location gave tone, so I'm going to assume that is the C2-8 location on the black connector. I'll take a picture here shortly and post it showing the location that I got continuity from. It was good, clear tone as well.

I had to stop testing there because of the rain. I typically don't like back probing wires, but I don't see a very good way to try and get a T-pin to the backside of that plug for testing, but I'm going to check again here shortly.

Will post and update soon.
 

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Update, I was able to get the plastic cover off the back and verified the location I probed was indeed the "8" location. So I had good continuity to the lower right socket at the relay location, still good. Using the same t-pin that I tested continuity to the fuse box, I plugged the ECM back in and tested to see if it was giving off the prime signal to the pump. It did not.

So to recap, the ign. switch appears to be giving power to the ecu. The pump will run when jumped with a 12v source. All fuses are good. I tested the C2-8 location from the ECM plug to the fuse box location, and I had good continuity, and lastly the ECM doesn't appear to be giving the prime signal.

Looks like I need to order up another reman ECM to me!
 

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I'm always hesitant to blame the ECM since a lot of the time after replacing it, I find it was something else. One other quick test to do is to see if it will run with the pump powered thru the test connector. If it does start, then at least you know that the pump not running is the only problem, plus it's easy to do. If it won't start, then there really isn't much to be learned because the ECM could have developed a bunch of other problems on top of the pump signal. By the way, is it getting spark?
 

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I'm always hesitant to blame the ECM since a lot of the time after replacing it, I find it was something else.
I have to agree. They are rarely the issue, but if you are sure you have exhausted every other possibility...

Try spareecm on ebay if you have to go that route. $70 shipped and programmed to your vin. You'll still need to do the 30 minute security relearn. Rhotpursuit can vouch for them. That's for a 16228016 non-flex Tutu.
 

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Another thing to check is ECM grounds. On the ECM, three grounds are on both ECM connectors - C1 18, C1 60, C2 64. All wires should be blk/wht. They all terminate on ground lug g103 located on the engine just above the oil filter. It's not uncommon for that lug to get corroded.
 

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Discussion Starter #16
Another thing to check is ECM grounds. On the ECM, three grounds are on both ECM connectors - C1 18, C1 60, C2 64. All wires should be blk/wht. They all terminate on ground lug g103 located on the engine just above the oil filter. It's not uncommon for that lug to get corroded.
I'll definitely check those before buying another ECM. I'll also see if it fires up with jumping the fuel pump. I haven't had the chance to do anymore testing lately. Hopefully today I can get to it.
 

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Discussion Starter #17
So here's the update so far.

I checked all three grounds at the connectors, and all of the grounds are good. I jumped the fuel pump at the fuse box to the test connector, lots of pressure, but will not start. Still no response from ECM via a scan tool.
 

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Discussion Starter #18
Final update,

I got a replacement ECM in today. On oldeerslayer's advice, I purchased an ECM from sparecm, ebay. Got it in the mail today, ran through the security learning phases, and she fired right up. Runs great again. For 70 bucks with a 1 year warranty, why not. Worth a shot.

Thanks everyone for the advice and help with troubleshooting.

Cheers!
 

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Glad you got it fixed. Although ECM's rarely fail and I really hate recommending replacing them, especially online, I guess you were one of the unlucky few that did need one.
You did a good job of checking every other possibility first. :clap:
rimara also did a good job of telling you all the things to check. :bowdown:

Makes me wish I had one with a Tutu.
(Never happen)
 
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