2000 2.2 low volts to Ignition Control Module

It's me again with the non starting S10. While checking voltage to the ICM, it started out at 12.5 volts from the pink wire just after a no start situation. While checking connections to sensors, wiggling wires for shorts and checking fuses, my power went down to 2.3 volts at the pink wire to the ICM. I noticed my headlights flashed when I pulled the 20A Ignition fuse in the box on the left fender. Inside I noticed the SECURITY light was on. After re-cycling the key and the fuse back in, the SECURITY light goes out after turning the key on. Could I have triggered the SECURITY system to cut my volts back to 2.3. I checked pink wire power into the PCM and get 12.5 but the pink wire out is giving 2.3 so the computer is where it's getting knocked down. Can I do something to reset the computer? Maybe the computer has been the issue all along? I've replaced most of the sensors with is ongoing issue. Check the other trox posts for the background if you haven't seen them yet.

HOLD UP! I just found the 15A fuse for the ECM 1 blown. Now I have 12.4 volts back at the coil. Now I'm back to running but very hard to start after the first start of the day (which is super fast). By very hard, I mean it cranks over a lot and will sometimes catch and go and sometimes it won't start at all, just crank. I've put a different ICM and coils in. Replaced both O2's, crank pos., and cam sensor. Have no codes and shooting ether in while cranking does nothing. I've done more, read previous posts from trox please. I'm going to check voltage from the computer the next time it happens, will let you know.

do you have a scan tool capable of reading data stream?look at coolant temperature sensor.an out of range coolant temperature sensor could cause starting problems.try spraying some carb cleaner into throttle body when will not start or hard start and see if it helps....would tell you if a lean condition was present.get a spark tester and see if good spark to plugs.why do you think ignition related?

The coolant sensor has been replaced. I have shot ether in the throttle body in the no start condition with no effect. A friend has a Snap-On scanner. Not sure if it will capture streaming data though. What should I look for if it does? My first thought back a couple months ago was a fuel pump but I put a gauge on it and it and the regulator check good. I have a few posts now from back when the pump pressure was the idea to now. Search trox posts from the last 3 months to see where I've been. It's a long story. Parts replaced so far: both O2 sensors, crank position, cam, water temp sensors, No codes, no SES light. Runs good when running. Swapped ICM and coils. New wires and plugs, fuel and air filters.

OK, I took it to my friends and put the scanner on it. There is no SES light on now. I got a code P0463 for my fuel level sensor A circuit hi output, Tank is full. I've had this code for a while because my gauge flips back and forth especially when full. Not too concerned with this and willing to live with a bad sending unit since it's part of the pump and costs crazy money. He checked BCM codes and found U1255, Generic/Class 2 Communication Fault. Any ideas on this code? I also got U1016, Lost Comm to ECM/PCM/VCM. I think this may have been triggered when I was pulling fuses under the hood. When I pulled the 20A IGN fuse the lights flashed and the SECURITY light came on the dash. I've driven it 20 miles today to my friends and back with no Security light. I've had the slow to light off issue since the first start this morning but it still started eventually each time and got me home. Could this be a ground issue for the computer? Is there a common ground point I can look at for the computer?

try holding gas pedal to the floor and see if it helps starting

if I had vehicle I would look at ignition on analyzer.does it matter if engine is cold or hot after first start of day when hard start is present?if engine ever does not want to start?if so check for spark with a spark tester.hard to tell where your problem is without testing equipment.

just recently working a 1994 s10 with hot/warm start issues.

the ignition control modules is a very likely failure. also if you feel some misses at normal operating temp this is how it begins to act up.

the module will also prevent fuel pump operation as well as not send ignition coil pulses.

scan tools are of no help.

I went to autozone. called first. they have an icm tester made by wells just for AZ. sure enough my ICM tested bad. I got a new [ dr140 ] icm for 47.oo .

this ICM made by wells is better than what was used in my 1994. circuit components are faster and more reliable.

normally these act up when they heat up. ICM comes with heat sink compound.

I've swapped the ICM with another supposed good one with no luck. I can take my original in to AZ to have it checked. The truck don't miss a beat when it runs. I'm thinking of putting a block of dry ice on the PCM after its been run to see if that makes a difference. If it don't don't make a diff to the PCM, I'll try it on the BCM. With the BCM centered low under the dash, I'm wondering if having the heat on more now its colder out has made this more pronounced. I did notice it was better when the hot weather broke back in September but only for a couple weeks.

I've swapped the ICM with another supposed good one with no luck. I can take my original in to AZ to have it checked. The truck don't miss a beat when it runs. I'm thinking of putting a block of dry ice on the PCM after its been run to see if that makes a difference. If it don't don't make a diff to the PCM, I'll try it on the BCM. With the BCM centered low under the dash, I'm wondering if having the heat on more now its colder out has made this more pronounced. I did notice it was better when the hot weather broke back in September but only for a couple weeks.

when it fails check for spark. you stated a shot of the starting fluid did nothing so I would guess the problem is in the ignition . take off the cap and check the pickup coil. make sure the ignition coil is good do the ohm tests/look for any arcing.

today I took out the 94 s10 changed oil and testing run the ICM I put in from autozone works great.

bring both those ICM's to auto zone for test , then thats out of the way. have them test those modules 3X .....that will get them hot so it will be a good test !

I've had the ICMs checked at AZ, both are good and the newer of the two is back on the truck. Ran the truck and checked voltage to and from the computer (pink wires) to ICM and found within .3 volts both on first start ( 1 to 2 cranks) and later starts when starting was less than perfect (4 to 8 cranks or turnovers) I just got a SES light so I'm taking it to O'reiley's tomorrow to see what it is.
Before going to O'reiley's, Today I'm starting the truck on the hour, every hour to see what it does. The first start was at 9:30 AM and it fired up quick as usual on the first start of the day. I only let it run for 20 seconds or so and not get warmed up. I started it again at 10:30 and it started quick again. I let it run for about 15 seconds again so not to get warm. Started again at 11:30 and got a quick start again and didn't let it run long (about 15 seconds). Started again at 12:20 and got a quick start again. That's 4 good starts in a row (probably because I'm not letting it get warm) I let it run for 10 minutes this time. Checked again after 1.5 hours and got the slow start, (took 8 to 10 cranks or turns of the motor. Waited an hour and plugged an old O2 sensor in for the heck of it, still got the slow start. On my way the O'Rieley's to see what the code is.

I've had the ICMs checked at AZ, both are good and the newer of the two is back on the truck. Ran the truck and checked voltage to and from the computer (pink wires) to ICM and found within .3 volts both on first start ( 1 to 2 cranks) and later starts when starting was less than perfect (4 to 8 cranks or turnovers) I just got a SES light so I'm taking it to O'reiley's tomorrow to see what it is.
Before going to O'reiley's, Today I'm starting the truck on the hour, every hour to see what it does. The first start was at 9:30 AM and it fired up quick as usual on the first start of the day. I only let it run for 20 seconds or so and not get warmed up. I started it again at 10:30 and it started quick again. I let it run for about 15 seconds again so not to get warm. Started again at 11:30 and got a quick start again and didn't let it run long (about 15 seconds). Started again at 12:20 and got a quick start again. That's 4 good starts in a row (probably because I'm not letting it get warm) I let it run for 10 minutes this time. Checked again after 1.5 hours and got the slow start, (took 8 to 10 cranks or turns of the motor. Waited an hour and plugged an old O2 sensor in for the heck of it, still got the slow start. On my way the O'Rieley's to see what the code is.


I would make sure the ECT not the guage temp sender is good.

if the ECT is not putting out the correct resistance when the engine is warm this hard start is quite possible. ect should be on the intake area

Thanks jcaT, The code I have is P0460, Fuel level circuit issue I've had for ever. The gauge flips back and forth and brings on the Low Fuel light mostly when full.
Anyway...How can I check the ECT (Engine Coolant Temp??) The sending unit was one of the first things I replaced. I can see it with the scanned hooked up and it looks normal when running. I'm close to getting a PCM/ECM from Ebay or local but don't know if I get it local, will it need to be "Flashed" before I can use it if I get the same part number unit? I can get one from Ebay flashed and ready for my VIN for about $65. Any way to check ECT or just get a PCM/ECM?

Thanks jcaT, The code I have is P0460, Fuel level circuit issue I've had for ever. The gauge flips back and forth and brings on the Low Fuel light mostly when full.
Anyway...How can I check the ECT (Engine Coolant Temp??) The sending unit was one of the first things I replaced. I can see it with the scanned hooked up and it looks normal when running. I'm close to getting a PCM/ECM from Ebay or local but don't know if I get it local, will it need to be "Flashed" before I can use it if I get the same part number unit? I can get one from Ebay flashed and ready for my VIN for about $65. Any way to check ECT or just get a PCM/ECM?

on the 1994 v6 s10 there are 2 temp senders. one on intake for computer the other for temp sender. both look the same but are different.

could also be the connector to it.

remove the connectors to the pcm and be sure the pins are clean .make sure the engine grounds for the pcm are also clean. pcm will get damaged or mess up if the grounds are corroded..

make sure the fuses are tight in the socket. some have had problems with the sockets not holding the fuses securely. this is when the fuses are rocked too much on removal.when the start problem comes measure the voltage at the ignition fuse see if its dropping.

auto zone you give the vin # when ordering the pcm. that way it is flashed to the vehicles spec.

keep the old PCM until your sure its fixed...

Is there a second water temp sending unit on the 2.2 engine? The water temp signal shown on the scanner should be the signal used by the PCM correct? If I pull the connector on the only sending unit I see at the front of the motor and the signal goes away, that would confirm it's the only input for water temp and should throw a code if it's the only water temp input.

Is there a second water temp sending unit on the 2.2 engine? The water temp signal shown on the scanner should be the signal used by the PCM correct? If I pull the connector on the only sending unit I see at the front of the motor and the signal goes away, that would confirm it's the only input for water temp and should throw a code if it's the only water temp input.

I mentioned the sensor because it is possible you installed the incorrect one or you may have 2 temp senders. not too familiar with the 2.2 engine.

with your issue though it is quite possible the sender is off. recheck with other part store that you have the correct one. measure resistance at room temp and at boiling point 212 deg f compare new with old.

the scanner should show the ECT temp .is this indicating what you believe the engine temp is ?

Well I took autojoe's suggestion from several replies back and have been putting the gas pedal to the floor to start after the first start of the day. THIS WORKS...I know I haven't fixed anything and there is something causing this hard to start condition in the afternoons but I've been driving the truck to work for 2 weeks now and it has started every time. There have been a couple times I just held the pedal half way and it didn't start as well. If I hold it all the way to the floor, it cranks maybe 2 rotations and fires up strong, (no sputtering like it did when I left the pedal alone) I'm thinking the computer is not resetting or setting for the warm start condition. Don't know if this is a timer or temp issue but hey, it starts. I've tried to duplicate the no start at home to see if I can get into the no start and back out by putting the pedal down but it hasn't "not started" for me yet. Thanks to autojoe and j cAT for sticking with me on this.

when you hold pedal to floor the pcm enters a clear flood mode and will lean out injectors to 16:1.maybe leaking injectors?too much fuel?best way would be to do a injector drop test but need a special tool for this that costs about maybe 300 dollars and use with a fuel pressure gauge......try adding to 1/4 tank gumout 2x concetrate.....I heard it works good but add to 1/4 tank.I have a otc setup at my shop you run through fuel rail.sometimes you have to take to a shop with specialized equipment if agony gets unbearable.even a ggod scan tool has its limits.if you do take to a shop make sure they specialize in electrical/diagnostics and ase certified.just some thoughts.are you sure fuel pressure regulator is not leaking through vacuum line?

Thanks autojoe.
I checked the fuel pump regulator when I was checking fuel pump pressure back at the beginning of all this. It checked good and I had no fuel in the vacuum line. I think I'll live with the "pedal to the metal" untill it warms up. I put an injector cleaner through it a while back but not at 1/4 tank. I try not to run below 1/4 if I can help it because of fuel pump worries. I think I have another bottle of 2X on my work bench.

i just wanted to mention that temp senders have one wire and temp sensor have 2 wires yellow and brown.newer vehicles dont use senders they use the coolant temp sensor.snap on scanner will do data stream on this vehicle.....with engine hot would have to use a temp gun and point at the thermostat housing and compare to the reading of the cts on the scan tool.see if any stored codes in the pcm.u code still there?getting fuel from somewhere fuel pressure not higher than normal and no leaking injector and regulator not leaking......I would look at your short term and long term fuel trims to see if pcm is compensating for a lean or rich condition.they should be plus or minus 10 percent.wish i could be more help.