I had a no fuel pump working issue. I purchased a new one from shosource. It powered the FP one day but not the next. I tested in and outputs per info found on site. I found all testing to be correct accept can't get pwr output on pin 5. Could something short out the new ccrm and how to find it. Thanks Plumber
ccrm
- Thread starter plumber
- Start date
Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.
SHOrod
Torrie Tuned
What year of SHO are you working on? I may still have the factory service manual info to be able to suggest a way to bench test the CCRM.
BaySHO Performance
SHO Member
Best way to find the problem when initially turning the ignition on to run the pump and prime the rails: check for voltage at the cutoff switch in the trunk. Voltage = bad pump. No voltage = bad CCRM.
Thank you for responding. Is it really that cut and dry. Plumber
Thank you for responding. I have a 1993 MTX 3.0. IT is a M ccrm. Plumber
SHOrod
Torrie Tuned
I would suggest that it's not. Since you've already verified you do not have output for the fuel pump from the CCRM, there's no need to test at the cutoff switch. Also, since two CCRMs perform in the same way, it's worth looking at the inputs to the CCRM versus just assuming you have two bad CCRMs.
I'll take a look later this evening at the wiring diagram to see if there's more suggestions I can offer.
-Rod
BaySHO Performance
SHO Member
Assuming no problems with the wiring.
SHOrod
Torrie Tuned
Sure, but power leaves the CCRM and goes to the shutoff switch, so he still needs to have power out of the CCRM to be able to determine there's a wiring issue if there's no voltage at the shutoff in the trunk.
As the OP has already determined, there's no power coming from terminal 5 of the CCRM. Plumber, I assume you know that power should only be present at terminal 5 for a matter of a second or two after the key is turned to Run, correct? Having a meter with a Max Hold feature or using a test light that you can see from the driver's seat may work best for this measurement. If you'd confident that was checked correctly, then make sure you have battery power to terminals 8 and 12 at the CCRM. These yellow wires should have power at all times. Also confirm you have battery power at CCRM pin 10. This Black/Orange wire should have power at all times. If those are good, then check for battery power with the key in Run to pin 13 (Red/Light Green wire). Confirm you have a good ground to pin 18 at the CCRM (Tan/Light Green wire). If those are all good, then you need to check for the enable signal to toggle during the first second or two of turning the key to Run. The enable wire is the Light Blue/Orange wire at terminal 11. I'm pretty sure this wire is active low (meaning grounded to enable the fuel pump) but I'm not 100% positive on that. It may be active high.
Please post back with what you find after making the above measurements.
-Rod
As the OP has already determined, there's no power coming from terminal 5 of the CCRM. Plumber, I assume you know that power should only be present at terminal 5 for a matter of a second or two after the key is turned to Run, correct? Having a meter with a Max Hold feature or using a test light that you can see from the driver's seat may work best for this measurement. If you'd confident that was checked correctly, then make sure you have battery power to terminals 8 and 12 at the CCRM. These yellow wires should have power at all times. Also confirm you have battery power at CCRM pin 10. This Black/Orange wire should have power at all times. If those are good, then check for battery power with the key in Run to pin 13 (Red/Light Green wire). Confirm you have a good ground to pin 18 at the CCRM (Tan/Light Green wire). If those are all good, then you need to check for the enable signal to toggle during the first second or two of turning the key to Run. The enable wire is the Light Blue/Orange wire at terminal 11. I'm pretty sure this wire is active low (meaning grounded to enable the fuel pump) but I'm not 100% positive on that. It may be active high.
Please post back with what you find after making the above measurements.
-Rod
Thank you so much. I will try this by the weekend and let you know what I found. Plumber
Hi. Thanks for taking time to help me. I don't know if I did this right but heres what I got. Still no pwr on pin 5. Have pwr on both pin 8 and 12. No pwr on pin 10. Pwr to pin 13 with key on. Now I'm not sure how to check for good ground. A wirinr dia. I found shows pin 15 as ccrm ground. If I do an ohms test with pos lead to 15 and neg lead to a ground by radiator it reads 0. If I do exact test on pin 18 I get I think a reading on tester of 96. k. Any help would be much appreciated. Thanks again Plumber
SHOrod
Torrie Tuned
I was a bit unclear in my original post. What you found is correct, pin 15 is the CCRM ground. Pin 18 is the fuel pump ground. I believe this pin should have ground potential on it to close the fuel pump relay. If you were to tie this lead to ground (through a test light or resistor to limit the amount of current) it should activate the fuel pump in a properly working and properly powered CCRM. I'm pretty sure you will need power to pin 10 though for the fuel pump to work. Per the factory wiring diagram, pin 10 should have power at all times. If you do not have power there, you may have a bad 50 amp fuse in the engine compartment fuse box. The fuse may be labeled as "Cooling Fan."
Also, since the CCRM also controls the radiator cooling fan, please make sure everything is clear of the fan when making these measurements just in case something you do causes the fan to run.
-Rod
Also, since the CCRM also controls the radiator cooling fan, please make sure everything is clear of the fan when making these measurements just in case something you do causes the fan to run.
-Rod
Thank you. I will check fuses tomorrow. Do you mean that if I pushed test light probe into wire pin 18 and touched other end to a ground I should hear FP. would key have to be on? Sorry not real clear with electrical testing.
SHOrod
Torrie Tuned
Correct, I'm pretty sure that if you were to backprobe the terminal at pin 18 with the probe of a test light and connected the clip to ground, the test light would light and the fuel pump would run after you determine why you do not have power to terminal 10. Based on your measurements though, there's a good chance when you figure out why you don't have power to pin 10 the fuel pump will work as designed with either of the CCRMs.
-Rod
-Rod
Hello Rod. I really appreciate your help. I got a car manual from library. I don't know how to read elec dia. very well. I wanted to see if this was right. It looks like pin 10 gets pwr from cooling fan fuse in engine compartment. Its a BK/O wire. Now am I suppose to have pwr all the time from the fuse box to ccrm. I do have pwr right where BK/O leaves fuse box. So do I have to take apart wire harness and trace BK/O wire from fuse box all the way to ccrm? That is going to be fun. Thanks Plumber (Steve)
SHOrod
Torrie Tuned
Do you have power to pins 1 and 2 at the CCRM (also Black/Orange)? If so, you could just jumper from those pins to pin 10 since they are all on the circuit. In that case, the issue is likely to be at the common splice for those three wires. If not, I then suggest checking for continuity between pins 1, 2, and 10. If you have continuity between all three but you're not getting power, then the splice is good and your issue lies between the splice and the fuse box.
You could also try providing power to pin 10 with a fused jumper wire to the battery to confirm that the fuel pump then primes as it should.
-Rod
You could also try providing power to pin 10 with a fused jumper wire to the battery to confirm that the fuel pump then primes as it should.
-Rod
Thank you so much for helping me. I will try that this weekend.
Hello. Well I think I made some progress with your help. I got lucky finding c105 connector bad. I did a continuity test like you said and found no continuity through it. It was corroded bad. I temporarily cut it out and put it together with 12 ga wire and wire nuts. I went to start it and with old ccrm pump came on but stays on with no start. I installed new one and when starting the pump and fan run continuous with no start. Can the pump make noise without pumping? Should I get a gage to check fuel press. I also had pwr leaving ccrm on pin 24 to pcm and pwr on red wire to injector when starting. Any ideas? I also contacted shosource and they're willing to test ccrm if I send it back.
Hello Rod. I also forgot to mention that I was able to pull codes before but now if I jumper the DLC or try to ground FP nothing happens
SHOrod
Torrie Tuned
Good find on the C105 corrosion!
If the pump is bad or the line from the pump to the engine is restricted (fuel filter, etc.) the pump can make noise but not pump. However that is not a "feature" of the pump so checking for fuel pressure at the fuel rail would be a good thing to check, along with spark.
Your current scenario has me looking at the diagram to try to understand what could cause the fuel pump to run continuously. Obviously it would seem something is holding the enable line at ground potential, but I don't understand the difference yet between "LFP" and "HFP." I'm not sure if that's "Low speed fuel pump" and "high speed fuel pump" or something else. I think these are both enable lines, even though one is labeled as "LFP GND" so if either one is shorted to ground it might explain why the pump runs continuously. A quick and dirty might be to disconnect the PCM and see if the fuel pump still runs. If so, then it would seem you need to determine where the short exists between the PCM and the CCRM for pins 11 and/or 18.
I'll see if I can figure out the difference between LFP and HFP.
-Rod
If the pump is bad or the line from the pump to the engine is restricted (fuel filter, etc.) the pump can make noise but not pump. However that is not a "feature" of the pump so checking for fuel pressure at the fuel rail would be a good thing to check, along with spark.
Your current scenario has me looking at the diagram to try to understand what could cause the fuel pump to run continuously. Obviously it would seem something is holding the enable line at ground potential, but I don't understand the difference yet between "LFP" and "HFP." I'm not sure if that's "Low speed fuel pump" and "high speed fuel pump" or something else. I think these are both enable lines, even though one is labeled as "LFP GND" so if either one is shorted to ground it might explain why the pump runs continuously. A quick and dirty might be to disconnect the PCM and see if the fuel pump still runs. If so, then it would seem you need to determine where the short exists between the PCM and the CCRM for pins 11 and/or 18.
I'll see if I can figure out the difference between LFP and HFP.
-Rod
SHOrod
Torrie Tuned
LFP = Low speed Fuel Pump, so I assume HFP = High speed Fuel Pump.
Similar threads
