Cold start valve not firing like it should..

[painterdave72]

so im at a loss here.. i have a new thermotime switch and my cold start valve works fine with the plug swap.. just wont fire when cranking normally on a cold engine.. outside temp is about 45 degrees.. i had some corrosion on the spade connector on the starter solenoid for that wire so cleaned it off and did a new connector... i have about 9.5 volts during cranking at both terminals on the cold start plug.. that is correct yes/?? also have about the same voltage at the actual thermotime switch.. there is nothing else really in the circuit so i dont know what is going on.... any suggestions would be spectacular.. thanks....ps.. i have read the service bulletin that houston did a while ago when warren was there.. and have also talked to mike at midwest.. but still not working.....

[Bitsyncmaster]

When I first got my car the CSV never fired. That problem turned out to be a bad bulkhead connection that had 70 ohms. A pain to find since the wiring on my car did not match the schematic. There is a jumper in my bulkhead in that circuit.

[painterdave72]

my car has never had this issue till now.. so thats why i got a new thermotime switch.. but there is voltage at both terminals on the csv when cranking so this makes no sense....

[painterdave72]

there is no voltage present at the csv plug when cranking... only voltage present is on the one wire tested separatly... but testing for voltage between the 2 when cold cranking there is none.. and i ohm tested the thermotime switch this morn on a cold car. .its at54.5 on the one terminal and like 3.4 on the other.. wouldnt that indicate its not good???

[Bitsyncmaster]

Test the white/red wire on the CSV first. It must have 12 volts when cranking. You can pull the white/yellow wire off the resistor block to prevent the engine from starting. If that wire gets 12 volts then verify the blue/black wire on the CSV is grounding (has 0 volts) when cranking.

That will point you which wire to continue tracing back to find the problem.

It's best to leave the CSV plugged in for these tests so use a needle to probe through the insulation of the wires.

[82DMC12]

Test the white/red wire on the CSV first. It must have 12 volts when cranking. You can pull the white/yellow wire off the resistor block to prevent the engine from starting. If that wire gets 12 volts then verify the blue/black wire on the CSV is grounding (has 0 volts) when cranking.

That will point you which wire to continue tracing back to find the problem.

It's best to leave the CSV plugged in for these tests so use a needle to probe through the insulation of the wires.

Dave, I've been trying to help Painterdave with this problem via text since we are both in Kansas City. I checked my good, spraying CSV last night with a stone cold engine and my DVM only shows about 9V when the engine is cranking. I'm guessing this is just because of the delay a DVM often has, and if we checked mine with an analog/needle meter it would read 12V. Don't think my visually confirmed spraying CSV would spray with only 9V - and Dave is only getting 9V on white/red at the TTS when the starter is cranking too (also measured with his own DVM).

[Bitsyncmaster]

Dave, I've been trying to help Painterdave with this problem via text since we are both in Kansas City. I checked my good, spraying CSV last night with a stone cold engine and my DVM only shows about 9V when the engine is cranking. I'm guessing this is just because of the delay a DVM often has, and if we checked mine with an analog/needle meter it would read 12V. Don't think my visually confirmed spraying CSV would spray with only 9V - and Dave is only getting 9V on white/red at the TTS when the starter is cranking too (also measured with his own DVM).

When your cranking the engine, the battery probably drops to 11 or 10 volts because of the 150 amp load of the starter. The battery wiring will also drop some voltage. 9 volts probably is the normal you will read at the CSV. When I said 12 volts I mean battery voltage. I think the CSV will open much lower than 9 volts.

[82DMC12]

When your cranking the engine, the battery probably drops to 11 or 10 volts because of the 150 amp load of the starter. The battery wiring will also drop some voltage. 9 volts probably is the normal you will read at the CSV. When I said 12 volts I mean battery voltage. I think the CSV will open much lower than 9 volts.

Thanks for the explanation!

[Bitsyncmaster]

FYI:

10 foot of 4 AWG wire will drop 0.3795 volts at 150 amps. Probably the ground side is also dropping more or less. I never measured the ground resistance but it probably has 10 feet of wire drawing that same current.

[David T]

If the CSV is working when you do the plug swap your problem is either the wiring or the TT switch. Make sure the wire to the TT switch is on the correct terminal on the starter. Make sure the TT switch is actually grounded, ie, do NOT use teflon tape or pipe dope when installing the TT switch. Make sure the plug to the TT switch is not damaged or modified, if you get the polarity wrong you can burn it out in an instant! The TT switch will not fire the CSV if the engine is too warm so you can only do testing on a cold engine. If you crank it for a while the TT switch will also not fire the CSV. Best way is to prove out all of the wiring and then try testing the TT switch on a cold engine. If it still won't work, the TT switch is bad.

[painterdave72]

the connection had some corrosion at the starter so i cleaned it up and put a new spade connector...the car fired right up this morn.. but i did an ohm check on the thermotime switch when it was dead cold from sitting overnight.. it had like 55.4 on one terminnal and 3.4 on the other one.. shouldnt the one terminal be 0 when cold??? this is a new switch from dmcmidwest less than a month ago.. i also tested and confirmed the red white wire has voltage this morn when cold when i checked it by itself.. but when checking both on the csv plug together there is no voltage when cranking for a few seconds which there should be.. unless the element heats up in 3 seconds and nullifys that out???/ but like i said the car fired right up no problem....and the only place the 2 wires go to are into the bulkhead connector to go to the hot start socket.. so if the thermotime switch measures like it did when stone cold wouldnt that mean its a faulty new switch???? and by the way all my wireing is just about perfect as i replaced them all with nos wire harnesses a while back and my car never sees rain or wash or anything...