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When not hot, my 1994 940T always cranks and starts well using the ignition switch. On hot days after being driven, turning the ignition switch will not get the car to crank. The idiot lights will dim a little, and I think the starter solenoid moves a little, but not enough to make good contact and crank the engine. When I jumper the solenoid it cranks strongly and starts, every time. The battery is new, the ignition switch (behind the key switch) has been replaced, and it has a rebuilt starter. I have not replaced the neutral safety switch. Again, the failure to crank only occurs when hot and attempting to start with the key. Jumping the starter solenoid always cranks the engine in this situation. I suspected a bad wire termination at the battery, but putting cold water on those connections makes no difference.
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john
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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Hi John,
Kidding maybe... definitely deterioration in the barely adequate wiring in the 240 for the solenoid when the temp is extreme, if you can bypass it and get it to pull in.
There are two coils in the solenoid; one to pull in and one to hold. I think the wire gauge bringing the battery from the ignition switch through all the connectors, neutral safety switch, etc. is barely adequate when new, but I haven't pinpointed any particular spot in the 240 much less your 940.
I put this on my daughter's car a year ago thinking she may never have to use it, but she has, once.
Hard to pinpoint in the time you have after the engine compartment cools, but I think I've read stories saying a replacement solenoid / starter doesn't fix this common issue.
--
Art Benstein near Baltimore
Those who race through life finish first. (Darrel Hunsbedt)
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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Hi Art,
I have great respect for your talents and experience.
I didn't know the starter solenoid had two coils, one for engagement and one for holding. The solenoid coils I am familiar with have one winding. Counter EMF keeps the current from getting excessive when the plunger is pulled into place (for closing the contacts).
Since my starting problem happens only when the car is hot, in hot weather, I now suspect the termination on the end of the wire which actuates the solenoid. I am going to but a new crimp female spade fitting on it in a few minutes. The other wire junctions, and the neutral safety switch, don't get nearly as hot as the engine compartment.
I should have stated the mileage on the thirty-year-old car earlier, 423,xxx miles. That is a lot of cycles of starting and a lot of time. A long time ago I was working for an electrical contractor at a paper mill. We did new construction and maintenance. The paper mill would open up the motor control center buckets and take pictures, with an infrared camera, to find the warm terminations. During the annual shutdown I was given a stack of pictures showing the warm, or hot, terminations. I would have someone remove the old terminations and install new ones. Bad terminations looked fine. Only the IR photos would find the problems.
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john
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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Thanks for the kind words. I have the same great respect for your experience and talents and all the help you've given over the years.
That wire terminal at the #50 on the solenoid would be the equivalent of a person of interest in an investigation as I view it, both in its crimp over the wire and its grip on the lug. No other point in the circuit rises to a suspect level in my mind, given how infrequently the condition arises and how difficult it would be to catch the crime in progress. There are so many contacts and connections between battery + and that solenoid tab.
Having a screwdriver to get the car started might work for me, but I can't expect my kid to use it, nor could I afford to make a hobby out of the pursuit of the root cause in her car. Maybe if it were in my car presently...
One of the difficulties is, even with symptom present, checking voltage drop (say by piercing the insulation near the starter) is hard to compare against normal (who can provide new car readings anyway) between the temperature rise in the solenoid coils and the dropout of the engagement coil which pulls current through the brushes and starter winding.
So this hobby pursuit might take enough years to actually blame it all on climate change, attempting to replace parts of the #50 circuit until it doesn't happen every summer.
Here's a map of the 240 starting circuit. It shows both solenoid coils energized in the second drawing "Control solenoid pushes starter pinion..." I imagine the 9-series works the same under the hood, but is vastly different from there back in wire colors, terminals, etc.
I have a 1988 Bosch handbook devoting a chapter to starter design in which the drawings are a little easier to read and the text describes the operation step by step.
--
Art Benstein near Baltimore
Dad: Someone who hopes his sons will turn out to be just like him, and who is afraid his daughters will meet someone who did.
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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Hi John. Long time since we've heard from you. Hope you're doing well.
Based on everything you've said, the PNP neutral safety switch would be the top of my suspect list as long as you're happy it's not the starter motor/solenoid (like tapping hard on the solenoid with a 2x2 doesn't help?). I've had a number of nuisance, intermittent no-starts from that switch over the years, just not the hot and cold issues as you've experienced.
Locate the open pink wire remote start connector in the left fender wiring harness and jumper that to the starter solenoid (blue-green) to bypass the PNP switch. If it will now crank in KP-III then you've pretty much got it narrowed down to the switch (or perhaps the wiring to it).
The PNP switches are a real pain to get to, having to raise up the shifter assembly in its housing, and it's easy to break the two thin plastic mounting studs if you're not extra careful. Bending the star lock washers open one tab at a time using a pointy awl works for me. Once the switch is off and to the bench, you can pry it open for access to the contact area to clean it up and re-lube it with something like dielectric grease.
Be prepared for a solder connection to break in the process -easily fixed. I've never had to replace a PNP switch, always been able to resurrect them with a cleaning.
Only tip I've got for you is to use acorn nuts on the plastic studs for re-installation rather than the original star lock washers -so much easier to remove if you ever need to again. I forget if it's SAE 5/32", 1/8" or 3/16" acorn nuts that work fine as long as you only do them finger tight so as not to strip the plastic. Using a socket on a handle helps keeps them straight for threading on.
--
Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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While I'm thinking of it, in case it turns out you end up needing to replace the PNP neutral safety switch, I just remembered that the one for the '94-'95 AW70 trans (p/n 9130295) is no longer available. The one for the earlier '91-'92 900s and 700s (p/n 3544164) is the same switch and is available, you just need to unsolder and transfer the wiring connector. Also while I'm thinking of it, the ignition lock cable that goes to a threaded adjuster sleeve on the front of the shifter assembly needs to be slackened off if you need to unhook it from its pawl to remove the shifter. There's no adjustment spec that I can find, so simply count the faces as you back it off so you can restore the original adjustment. Adjustment doesn't appear to be that critical.
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Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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Thanks for the suggestions.
I have a spare shifter assembly which I may install. Prior to that I may test by installing a jumper at the electrical connector for the neutral safety switch, under the car.
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john
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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Hi John. I'm not sure what you mean by using a jumper under the car to bypass the shifter assembly PNP switch. Only wire underneath the shifter in the '95 940s (should be same as your '94) is for the overdrive solenoid. The PNP switch connector is on the left side of the tunnel, just forward of the tunnel console, so will need the left console side panel off for access unless you can dig it out from above below the ashtray.
That pink wire remote start connector under the hood that many people have trouble finding should be there buried in the left fender harness. Leastwise, it's present on both my '95 LH 2.4 940s, NA and turbo. That's your simplest way to verify a PNP switch problem and if necessary to bypass it.
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Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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Dave,
Thanks for the input.
You are correct about the location of the connector for the neutral safety switch. Dumb me. I was thinking about getting under the car to disconnect the wire to the AW71 overdrive solenoid, when replacing the shifter assembly. I have a complete shifter assembly I can install, but I'll probably try the jumper around the neutral safety switch first.
I don't have a wiring diagram for the 1993+ 940s, but the 1987 wiring diagram shows the pink wire upstream of the neutral safety switch. So, it is still my prime suspect. What I don't understand is why it only happens when the car is warm, on a hot day. Maybe a hot starter solenoid takes more inrush current?
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john
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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John,
I have an email address for you but have no idea if you still use it. I sent a PDF file of the Volvo green book of the 1994 940 wiring diagram to that address this morning. If you didn't receive it please let me know.
You can email me a vguy240atyahoo.com That is a throwaway account.
Randy
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Any twenty minute job is just a broken bolt away from a three day ordeal
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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Dear johnsargent,
Hope you're well and stay so. An invisibly thin layer of corrosion can disrupt an electrical circuit. Most common metals expand when warmed. So, a wire with defective insulation - that is warmed by rising temperatures and/or the passage of current - may expand just enough to contact adjacent metal. That suffices to disrupt the circuit.
When temperatures drop - or the engine is off - the wire shrinks enough so it doesn't touch the nearby surface: current flows smoothly. As the distances involved are minimal, these problems are hard to see/diagrnose.
Hope this helps.
Yours faithfully,
Spook
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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With enough effort you should be able to find a copy of the 940 green electrical manual online. Try this link
https://procarmanuals.com/pdf-online-volvo-940-1994-wiring-diagrams-tp3904202/
Starter system begins on p42. I've also seen the '95 manual available for download somewhere, although I have my own copy of that one.
Yes, that no/poor crank when hot and a good crank when cold is a bit of a puzzler.
You've checked and isolated just about everything except for the PNP switch, so as much as these aren't classic symptoms for a failed switch, probably best to eliminate that next. When the PNP switch goes you can often get it to work intermittently by leaning/wiggling the shifter forward/back/sideways in Park or Neutral if it's the contact area that'd grungy, but if it's the contact wiper block that's grungy (or worn) then those tricks may not help. While I'm thinking of it, check for back/forward slop in the shift lever in case one or both trans linkage bushings are gone. First sign of that is usually intermittent operation of the backup lights, but it can also affect starting, especially in Park.
Same is true if it was the ignition switch starting to go -lifting or raising the key while starting or forcing it over hard will often get it to occasionally work. Maybe reach up underneath and double check that the electrical connector is on good and solid and that none of the wires are notably loose in the connector.
If you hadn't said you'd replaced the starter then a sticky solenoid would have been my first guess. The ease of solenoid movement could easily be affected by heat and expansion. Once you get past verifying the PNP switch, I'd put that re-built starter back on my suspect list. The fact you can directly power it and get it to crank may be as you say, giving it enough of an extra kick to now catch.
Keep us posted as you've now got me extra curious about the temp side of the equation here.
--
Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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Hi John,
I had that issue with my 740 and the only thing I didn't try was a NEW starter solenoid.
First wire brush the terminals at the battery including the piggy back wires on the positive terminal. Check each terminal end for corrosion where the wire enters the crimp, telltale dark blue or green is one tipoff for a bad terminal.
Lube with conductive grease, nickel or copper anti-seize or Penetrox-A.
When it doesn't start with the key, try putting +12 volts to the service port
in the engine bay near the power stage. See if it starts with the service port.
If that fails you can look for a binding solenoid and service or replace.
Probably the re-builder used the original solenoid.
Good luck, Bill
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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Thanks for the suggestions.
Everything was cleaned and wire brushed before I made the post. I used a copper based anti-seize, as usual.
The starter was replaced as an assembly. It cranks great if I jumper 12 volts to the starter solenoid.
I don't think my car has the service port for starting the car.
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john
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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Hi John,
I had the same behavior from two Bosch starters in my 740.
They would both quit dead, randomly, sometimes months between failures.
They started normally when shorting the solenid contacts with a big screwdriver.
I think that the solenoid and fork linkage etc, may be binding requiring
more current to engage. You could use a relay at the starter if the solenoid simply needs more current. That might be a good solution, relays are cheap,
and solenoids cost more than complete starters with the solenoid.
The service port for my 1993 940 breaks out of the high driver side engine bay harness just even with the drivers side of the battery. It is a single short pink wire to a plastic shell and it is a 1/4" female spade connector.
You just need a short jumper to the Positive terminal with the ignition in KPII
to start.
Good luck, Bill
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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Hi Bill!
Thanks for the suggestions.
The starter solenoid is fine. There are two electrical connection male spade fittings on the starter solenoid. One has the factory wiring connected to it, and gives power to the solenoid when turning the key. I have installed a "jumper wire" on the second spade fitting. When I touch the other end of this wire to the positive battery terminal, the starter works perfectly every time. Your suggestion of installing another small relay to provide actuating the starter solenoid is a good one. This is in effect, a small amplifier.
I found the pink wire buried near the Power Stage. It is in a blue connector. Giving the pink wire voltage draws a small spark at the battery, but gives insufficient current to operate the starter, just like turning the key does not. That is a clue, but I haven't figure it out.
I may use a fine tip probe to gently pierce the insulation in the wiring to take voltage reading while my reluctant assistant (wife) turns the key to the start position.
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john
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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Hi John,
Probably your ignition switch is OK.
In future use an alligator clamp and wire and make the connection at the service port. Just in case there's any hydrogen gas near the battery.
You can measure from the service port to the solenoid lug with the Blue-Green wire to see if you have a high resistance in that circuit. It should be only a few ohms with the shifter in Park. This tests for bad interlock switch and/or corroded connectors. Do this measurement with the key off.
You will be measuring the interlock switch and 3 connectors.
Bill
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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I don’t have any educated suggestions, but I will throw out a couple of things I might try if I was stranded somewhere with a similar problem.
Have you taken the positive post clamp off and cleaned the connections that are associated with the clamp bolt? I’m thinking that any corrosion could inhibit the delivery of the needed amperage to trigger the solenoid.
Have you tried moving the gear selector into neutral and trying to start the car with it in that position? Or perhaps moving the selector a bit on each side of neutral while holding the key in the start position?
Sorry, that’s all I got.
--
Any twenty minute job is just a broken bolt away from a three day ordeal
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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"Have you taken the positive post clamp off and cleaned the connections that are associated with the clamp bolt? I’m thinking that any corrosion could inhibit the delivery of the needed amperage to trigger the solenoid."
No corrosion observed. There could be some inside the crimped wire terminal on the wire leading to the ignition switch, but nothing observed externally and no swollen crimp fitting.
"Have you tried moving the gear selector into neutral and trying to start the car with it in that position? Or perhaps moving the selector a bit on each side of neutral while holding the key in the start position?"
I sure have tried that, but there is no change.
Thanks for the suggestions.
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john
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