Discussion in 'Gen 1 & 2 - Electronics & Audio' started by plumber, Mar 28, 2019.
Thanks again for your help. I will try that next week. Are you saying there are 2 pumps? Plumber
It sounds like just one pump and a current limiting resistor that gets switched in for low speed, high speed is full voltage. I'm not sure if internal to the CCRM that's a separate relay or not.
Only one pump for Gens 1-3. Dual pumps came into use with Gen 4.
Well still confused. I thought I was on the right track with finding the bad connector. I thought I would try to start it just for fun before I tried what you suggested. Now the pump doesn't come on when it did 2 days ago after fixing connector. So I will check pwr on 1,2, and 10 and 5 and 13 while starting again tomorrow. Was wondering if you had any ideas why pump came on right after connector repair and 2 days later nothing. Thanks plumber steve
No thoughts on that without understanding which power wires have power when and if the ground/enable signals are getting grounded.
Hello Rod. Here's what I did today. First tried key on with old and new ccrm and nothing. Then I checked wiring at both ccrms. PIns 1,2 and 10 still have pwr after fixing connector. Pins 13 and 24 have pwr with key on. Still no output pwr on pin 5 with either ccrms. I ran a wire from pos post to pin 5 with harness disconnected and pump runs. Then strangely turned key on and pump runs continuous with old ccrm. put new ccrm in and pump and fan run continuously. Lastly I pulled pcm harness and with key on fan runs but not pump. Sorry for long post. Thanks again for any thoughts. Keep wondering if with bad connector or something else hurt new ccrm. The other thing that bothers me is I was able before to pull codes from DLC and short fp to ground to run but now I can't. Its weird that after putting pwr to pin 5 the pump would then run with either ccrm. Thanks plumber Steve
Have you checked to see if you're getting ground from the PCM to pins 11 or 18? Do you have battery voltage at all times to pins 8 and 12? Have you tried pulling pins 11 and 18 to ground through a test light? Does that cause the fuel pump to run with the key on?
Thanks Rod. I will check tomorrow pwr to 8 and 12. I don't quite understand how to do the test on 11 and 18. Sorry but could you explain how to do those please? Plumber Steve
Pins 11 and 18 appear to close the Low speed Fuel Pump and High speed Fuel Pump relays when those lines are grounded. Usually the resistance through a test light bulb is low enough to activate a relay, so I'm suggesting clipping the wire of a test light to a good ground, then backprobing the CCRM pins 11 and 18 with the tip of the test light to attempt to force the associated fuel pump relay to close and run the fuel pump. With pin 11 this should serve the same function as grounding the fuel pump wire at the EEC connector, but it bypasses a few feet of wire and possibly a splice or connection.
Thank you Rod . I will try that tomorrow and let you know what happened. Plumber Steve
Hello Rod. I used a test light as you said on pins 11 and 18 and the pump did run. What do you think I should do next? Thanks again for your time. Plumber Steve
That suggests to me that the CCRM is working (at least mostly) correctly, has power where it needs power, but for some reason the PCM is not requesting the fuel pump to run.
Hello Rod. Is there any test I can do on PCM myself? I also was wondering that if I get pump to run by grounding at one of the pins or the VIP connector why won't it start. Is there an easy test for spark or to make sure the crank pos sensor is good ? Thanks again. Plumber steve
Those are very good thoughts. I wish I could say I had thought about that, but it is interesting that your car still won't start even though you can get the pump to run. That further supports that the CCRM may not be your problem here, but rather the PCM is short some input that it needs to enable the fuel pump.
I'm not aware of a way to bench test the PCM. Often the troubleshooting for the PCM involves a breakout box so that you can easily probe signals in and out of the PCM. There are easy tests for spark that range from just laying a spark plug wire with the boot slid back near a grounded part in the engine compartment and look for spark when engaging the starter to capacitive testers that clamp over the plug wires and connect to an oscilloscope. The easiest may be to use an old spark plug if you have one around and connect it to a plug wire, then lay that on a clean grounded part of the engine. I have an old spark plug that I soldered an alligator clip on to to make this easy.
There are ways to test the crankshaft position sensor as well using a DMM on the ACV setting then checking for voltage from the signal wire to ground while engaging the starter. The more error proof way to check this is with an oscilloscope to confirm the square wave pulse is consistent, but the DMM approach can at least identify a completely dead sensor (in which case you'll also want to confirm you have the 5V reference voltage to the sensor).
Hello Rod. Not sure what to try next. I did some looking around and found the crank sensor connector on top of engine. The connector down to the sensor has 4 wires and a single connector coming from the harness. But the connector going back the other way has 4 wires and a single wire connector that is disconnected from the harness. Now it looks like it maybe was connected to a frayed wire sticking from the harness that I think is what the diagram says is a shielded wire? Any thoughts? Plumber Steve
If you found a connector near the top of the engine I suspect you're actually looking at the Cylinder Identification (CID) sensor (aka: Camshaft Position Sensor). The Crankshaft Position (CKP) sensor is mounted at the crankshaft and the wiring diagram does not suggest any connectors for that harness other than at the sensor itself and at the Ignition Control Module. At the sensor itself there should be 5 wires as follows:
VBat (Red/Light Green)
IGND CS (Orange/Red)
PIP CS (Gray)
PIP PCM CS (Dark Blue)
The PIP PCM CS wire goes to the PCM and the PIP CS wire goes to the ignition control module. Considering the PCM doesn't seem to be controlling the fuel pump enable of the CCRM, I'd suggest checking for signal on the Dark Blue wire relative to power.
What color are the wires at the connector that you are referring to in your prior post? If they are Dark Green, Red/Light Green, Orange/Red, and Light Blue, that would be the CID sensor. Which of those wires is the one that is on the single wire connector that is not connected?
Hello Rod. Well the grey connector has these wires. One side has LB,DB,BL/O,R/LG with the frayed wire coming out of shielded harness. The other side of grey connector has DB,GY,O/R,R/LG, with a almost dark blue colored wire coming out of the harness with a small connector that is connected to another connector with a piece of white colored wire that is not attached to anything. I did pull one plug wire and put an old plug in it and layed on engine. Had wife try to start car and did see sparking on plug
Also should the CEL be on with key in on position and then go out when trying to start? Mine stays on when trying to start. Don't know if that means anything.
Are you saying the connector has 2 rows and 8 wires, or are you referring to wires colors on mating 4-wire connectors? I'm not finding anything that quite matches what I think you described.
Also, it's been too long since I've had my 1993 SHO to remember if the CEL stays on when the starter is engaged. I would have guessed that it went out when the starter is engaged but I'm not positive on that.
OK I posted a pic of the disconnected ? wire which I don't think has anything to do with original problem. The green arrow points to frayed wire coming out of a shield I think. I added the blk wire to the connector which originally had a 3 inch piece of dark white insulated wire attached. I don't know if they were ever connected to each other. THe connector on the right is going to crank pos sen. I don't know why one colored wire is different from wiring diagram.
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