fuel pump 60K issue

[Brian Smith]

Can anyone decipher the meaning of these measurements taken at the ccrm with the key in the run position and the fuel pump test point grounded:
(pin number/voltage reading) 1/12v, 2/12v, 3/0v, 4/0v, 5/0v, 8/0v, 10/12v, 11/4v, 12/12v, 13/12v, 14/4v, 15/0v ,16/0v, 18/4v, 21/0v, 22/0v, 23/0v, 24/4v...poking around trying to figure this out, too bad wiring diagrams may as well be in greek...

 

[Brian Smith]

does anyone know where the fuse box is located on a 91 sho. Its not ont he firewall in front of the driver below the master cylinder reservoir.
mabey i have a blown ignition circuit. Betty davis had that and had the exact same symptoms

 

[Brian Smith]

someone please give me something to work with here? :headbang: :headbang: :headbang: :headbang: :headbang:

 

[projectSHO89]

Third edit.

Pin 8 should be battery supply voltage.

Look for an open "Blue Fuse Link 'N'" near the starter relay according to the 91 Mitchell's.

This will also **** PCM power and will explain your inability to pull codes.


Steve

 

[Brian Smith]

there were three fusible links attached to the starter relay with blue wires after the fusible links. None of them were open...I did notice that my dome light failed to come on after I disconnected them to check them and reconnected them. How nice. It's really too late to do anything else tonight, not that i really have anything left to do but start hitting things with a wrench.

 

[Brian Smith]

So if pin 8 on the ccrm is not energizing that is indicative of my problem source. If I find the fault causing 0 volts to pin 8 have I likely found a solution to the problems as outlined? Steve do you know any other locations besides fusible link N that would cause pin 8 to be non functioning?

 

[projectSHO89]

I'm working off the Mitchell's from the Russian site and from some generic drawings as I do not have a 91 EVTM. Without that EVTM, all I can do is either trust the Mitchell's or make educated guesses.

I believe that if you find the reason for the loss of power to pin 8, you will be able to repair the car.

Look to see if there is a fuse link at or near the battery instead of the starter relay. The Mitchell's seems to indicate three links at the relay and at least one at the battery.

Steve

 

[Brian Smith]

ill check for the fuse link at the battery this evening. What is this mitchell's you reference? Is it an enectical systems guide book for the taurus? Where could one purchase one of these? Thanks Steve!

 

[Brian Smith]

all last night I hoped i would find a burnt out fusible link. This did not happen. The battery cables run directly from the battery to the starter relay. Power is distributed from that point. I searched and found several more fusible links branching from the main three fusible links at the starter relay. None of them were open. I could not find any other fusible links anywhere else in the engine bay. How much would one be expected to pay a mechanic to search for and find electrical glitches like this one? :jpshakeh:

 

[Brian Smith]

Possible solution?

Steve this is a question for you to consider. My problem *seems* symptomatic of a PCM not recieving power. I am basing this on a long search of older posts and similar problems. Having determined that my broken circuit is not due to a burned fusible link: perhaps my problem is with the wire which feeds the PCM? I believe that 12V in for the PCM is pin 1, at any rate a yellow wire...I ran a continutity check from the only yellow wire which exits the starter relay to the only yellow wire which enters the PCM (pin 1 I believe) and I found and open circuit. Is this because there is supposed to be an open circuit? To rectify this problem can I simply run a new yellow wire (with appropriate fuses in line) from the PCM to the starter relay? This is a leap, but it has been the source of exactly my problem in the past...What do you think? I dont want to do anything rash and fry my PCM...

 

[Brian Smith]

Please do give me a sanity check on this one...reminding me of something like no close calls in horeshoes and hand grenades...

 

[snowwind1990]

Pain

dude,I feel your pain,I am going thru the sams crap,with a '91.It started last week when we was in Ft. Worth,woman wanted me to change her battery cable clamps,I did so with some perty gold colored clamps from auto zone. We made it back within 1/4 mile from home when all of a sudden the car starts to lurching and acting like no power.The next day it started acting up again,lurching and doing some wild ****.It died,had it towed home.Ordered a fuel pump,dropped the tank and installed.COOL....or so I thought,she put some fuel in and I follow her on a test drive,3 miles later he goes the lurching crap again,feels like its starving for fuel.It dies again.YIKES!TOW TRUCK again.Well I'm ****** now.I drop the tank again to make sure I didn't pinch any wires and triple check the pump.Everything is fine.I start doing the voltage checks as you mentioned and they are almost exact to the T.After a day of reading and trying to ask people on SHOtimes for help I am no futher than you are in finding what the prob. is.I did change the ******* clamps with some $3.00 ones and guess what he fired right up.BUT......on a worse note the lurching came right back.I only drove 2 blocks.LURCHING again.I will do some more voltage test tomorrow.Please let me know how your deal is a going.

 

[projectSHO89]

PCM pin 1 is "Keep-Alive PWR". That means it is there on that pin only to support the memory backup in the computer.

The critical power supply for the PCM is supplied via the PCM PWR relay in the IRCM. It is supplied (input to IRCM) by IRCM pin 8.

Both of these power branches are listed as being supplied by the same fusible link.

If you were to jumper battery power to this circuit, connect it to IRCM pin 8 via a 20 A fuse.



Snowwind: Try disconnecting the CID sensor.

Steve

 

[snowwind1990]

Pain

CID

YYYYYY???????

If I can get Bart to AutoZone I could just have them perform a KOEO and KOER test....

Yes?????

 

[Brian Smith]

Steve,
Which pin # on the PCM is input power. What voltage should it be receiving?If I am to understand you correctly power enters the IRCM via pin 8, then is distributed from the IRCM via pin ? after the relay and enters the PCM via pin?. What are those two pins so I can check their respective voltages. Strangely, I re-checked pin 8 on the IRCM yesterday and got 4 volts...Now the car is just @#$%ing with me...

snowwind90,
Good luck, this electrical stuff is mystifying.

 

[Brian Smith]

bump...please a little help

 

[projectSHO89]

Can't be at the computer all the time. Have to leave and work, ya know.

Find the open circuit between the battery and IRCM pin 8. That one is the key. Without full battery power on pin 8, the PCM will never get power.

Snowwind: You could always run them yourself, it isn't difficult. Your symptom sounds much like a flaky CID sensor.

Steve

 

[Brian Smith]

Sorry Steve, Not meaning to be demanding or anything. I didnt get a chance to work on the car today anyway...Just didnt want my post to be buried under a flurry of new posts. I will post results of IRCM pin 8 trace. Thanks again.

 

[snowwind1990]

Repeat

Brian,
I once again urge you to please reset the PCM and clear it's memory. Disconnect the two cables and walk away for 10 mins. Come back, connect cables and do the procedure for reading codes....if you need direction in that, ask.
The SHO does not recognize the new wires., etc....

 

[Brian Smith]

I will try that tomorrow snowwind. Meantimes I jumpered pin 8 on the CCRM (yellow wire) with the PCM disconnected and guess what? When I turned the key the cooling fan energized. Every time I feel like I am about to see the light at the end of the tunnel with a solution in mind it gets dashed. Why would the fan energize? I can see what would lead you to believe this powered the PCM Steve, I checked out the translated russian wiring schematics and I can see that the yellow wire at pin 8 goes to the battery (starter relay) on one side and inside the module goes to the PCM relay. I start tracing the wire and, WTF? It branches...one yellow wire becomes two. At this point i stop trying to trace it, cut it about four inches from the CCRM and Jumper the short wire coming from the CCRM to 12V at the starter relay. Turn the key and I hear the fan come on. I didnt want to try it with the PCM connected at first just to be on the safe side. Now this fan thing has really got me scratching my head. Nothing like trying to do this all at 11pm so i can get to school tommorrow (my other car took a dump on me earlier today). What a week. :headbang: