Intermittent miss on number 6 cylinder low voltage on A11 terminal ecm

karst#9

Member
Ive been fighting an intermittent miss on cylinder #6, i changed every sensor checked grounds checked vacuum changed plugs tryed 3 different modules and coils different ecm different chip, i decided to probe the ecm pins and found terminal A11 cam high only had 6.70v. running should be around 11v. and b5 terminal crank reference had 3.64v. which should be 5.56. running. I was just wondering if this is a wiring problem or bad ground. I checked all grounds with a meter behind block, firewall ground good, ecm grounds good. New cam and crank sensor basically changed all sensors with good known ones or new ones. I was just wondering if im overlooking something or why the voltage is low. The ecm is getting full battery volts. I read on gnttype that the crank sensor starts the injector fire on number 6 and with the low volts would that be why its missing on #6.
 

karst#9

Member
Ive been fighting an intermittent miss on cylinder #6, i changed every sensor checked grounds checked vacuum changed plugs tryed 3 different modules and coils different ecm different chip, i decided to probe the ecm pins and found terminal A11 cam high only had 6.70v. running should be around 11v. and b5 terminal crank reference had 3.64v. which should be 5.56. running. I was just wondering if this is a wiring problem or bad ground. I checked all grounds with a meter behind block, firewall ground good, ecm grounds good. New cam and crank sensor basically changed all sensors with good known ones or new ones. I was just wondering if im overlooking something or why the voltage is low. The ecm is getting full battery volts. I read on gnttype that the cam sensor starts the injector fire on number 6 and with the low volts would that be why its missing on #6.
 

karst#9

Member
I found part of the problem i thought the orange wire was the ecm hot wire which was battery volts, I found out the a6 pink and black is the ign. ecm power off the fuse box and was only 13.05v. almost 1v less than battery volts with car running. i got a problem at the fuse box. I have never had a fuse box out of one of these, is there a ground behind it or plug in connections?
 

Chuck Leeper

Toxic old bastard
Staff member
The fuse panel has 2 plugs coming into it, from the engine compartment. Look at the engine side, and you'll see them.
The panel is held on w/ 2 long screws, on the inside face.
There's load of tar in the engine side plugs, so expect a mess.
Could be, there's some corrosion at the plug connections.
 

michael evans

Well-Known Member
The wires are over 30 years old. That and my engine harness had been cut on / repaired many times, so I put in a Casper's harness.
 

karst#9

Member
Thanks Chuck, im going to take it apart and look at it it actually varies on voltage inside the car, under hood its almost steady voltage
 

TurboTnZ06

Go on red!
I run Holley EFI and a Cruz engine harness, however, back in the day, check the voltage drop across the factory ignition switch. Back 10+ years ago I had to replace mine as it was losing voltage and that thing feeds everything... And its a total pain to swap that switch if its the issue too.
 

salvageV6

Daily Driver
There's a connector behind the glove box the ECM fuse power goes through that could be an issue. C437 foam covered easy to find by dropping the glove box door, pink/blk wires are the power ones.
 

Chuck Leeper

Toxic old bastard
Staff member
I think Earl Brown has a fix for the ign switch loading.
Moves the hi loads to a relay, and uses the switch to control the relay sw circuit.
 

karst#9

Member
I messed with it yesterday and got the correct volts to the crank and cam sensor by accident, i was probing the ccci wires and pushed on the light blue wire and the engine started running better, checked the voltage on the ecm it had correct voltage and the crank and cam sensor had correct voltage but the light blue terminal b on the cranksensor was up and down from 6.80 to 7.40v. The blue wire is the output wire and i dont know why the voltage varies, but i need to fix the low voltage inside the car. My question does the light blue terminal b wire just go to the ccci. and stop there, and does it work off a ground. The car runs a little better but # 6 cylinder is still not firing like it should. Im no electrical whiz by no means but you guys are some great help. I ordered a ccci splice from caspers but im thinking about putting a whole ccci harness in it just to make sure. Thanks
 

salvageV6

Daily Driver
I would change the spark plug and the spark plug wire to #6 first for that issue.

The CCCI fuse I believe only powers the spark plug coils in the CCCI, not the CCCI electronics.

IGN power on Pin P of the CCCI the the PINK/BLK wire comes from the ECM/IGN fuse which also powers the ECM A6, first via the IGN switch, then the 10A fuse then that connector I previously mentioned behine the glove box, then a splice called S457 where it goes to the ESC and MAF, ECM and CCCI module.
 

karst#9

Member
I changed spark plugs and different wire 3 different times on cylinder #6 its not in that ,also put a plug in the wire grounded the plug and checked fire it was ok on that cylinder. I will check the s457 splice i just havent got this far yet ,it has to be something inside the car wiring like that causing this, if camsensor finds #6 first, the signal must be weak to miss on #6 cylinder is what im thinking because of the up and down voltage. This is a t top car so corrosion is very possible
 
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