Dear Fellow Brickboarders,

Hope you're well. Car died in traffic: flat-bedded home.

Tachometer does not move at all, when engine cranks. This suggests the crank (RPM) sensor has failed. It was replaced 1K miles ago.

Code: 223 (Idle air control valve signal missing or faulty) doesn't explain no crank condition. Or, does it?

Thanks in advance for your help.

Yours faithfully,

Spook

Dear Fellow Brickboarders,

Hope you're well and Thank you, for your replies. Replacing the ignition coil and power stage cured the problem.

I separated the failed coil its power stage. The coil's pins had only slight corrosion, not likely problematic.

I used a multimeter to check the coil. The Volvo pocket data booklet - Cars (700, 850, 900) 1991-1996 provides values, in narrow ranges.

When I put the probes on the two round pins - and the spade connector - I got wildly varying values, in positive and negative ranges. I expected to get stable values, e.g., "1" (open circuit) or "0" (perfect continuity).

I was surprised to see disparate and wildly fluctuating resistance readings. This suggests that the coil indeed has failed.

I suppose I could test this by taking a "known good" coil (e.g., the one I installed, that cured the "no start") and mounting it on the power stage, that supported the failed coil. If the "new" coil works on the "old" power stage, that suffices to convict the "old" coil.

But I'd guess one or more amongst you knows whether or not extreme fluctuations in coil resistance readings proves failure.

I look forward to the benefit of your advice.

Thanks in advance.

Keep Well!

Yours faithfully,

Spook

I might be able to help you with the extreme fluctuations, as it is a common experience for me when making contact with aluminum terminals.

Aluminum is a good conductor of electricity. Its downfall in that role comes when using it for relatively low voltages which can't pierce the quickly-formed oxide. 12V is low, but the nominal 1.5 volts my multimeter uses to measure low resistances really has a difficult time with the thinnest of oxide layers.

Try your test again, immediately after cleaning the terminals with emery cloth or steel wool to see if you are experiencing what I have for many years. Visible corrosion isn't required to cause trouble.
--
Art Benstein near Baltimore

Life is like a roll of toilet paper.
The closer you get to the end the faster it goes.

I can't help you with extreme fluctuations in coil resistance to diagnose a bad coil- although it sure sounds suspect.

I too had a problem with a Rex/Regina car. After reaching operating temperature the car would die and when trying to restart it there was no spark. I suspected the coil/power stage assembly. That was confirmed by swapping in a known good unit.

The portion that you refer to as the power stage was a labeled Bendix 1367438. In order to determine the bad portion of the assembly I swapped out the coil from the good unit to the problem unit.

Test driving the car it would die after reaching operating temperature. Installing the coil for the Bendix replacement to the known good unit produced a combo that worked just fine.

Based on the swapping around I decided the power stage portion was defective and the coil was just fine.

I always have a travel box that I make sure is with any of our cars if we are traveling away from home. The Rex/Regina car (91 745) always has a coil assembly tucked away in the cargo hatch.

Randy
--
Any twenty minute job is just a broken bolt away from a three day ordeal

Have you started at the top of the list for troubleshooting? Spark, fuel, compression.

Have you removed the coil from atop the module it is attached to and cleaned the contacts there? I've never had a problem there but other people have reported corrosion on those contacts. I always take mine loose and clean them when I do a tune up.

Have you tried a good shot of starting fluid to see if you get a momentary run? That seems to be the easiest way to determine if it is a spark or fuel problem. However, correct me if I am wrong but without a signal from the CPS you will have neither fuel management nor ignition working for you when you crank the engine over.

Fuel injection relay and radio suppression relay are suspects for fuel management issues. Finally, have you checked to see that the cam is turning when you crank the engine?

I realize that this isn't your first rodeo and I'm probably suggesting things you know or have already tried.

Randy
--
Any twenty minute job is just a broken bolt away from a three day ordeal

Dear rstarkie,

Hope you're well. After ascertaining that: (a) fuel reached spark plugs; (b) spark test showed "no spark", I swapped-out the coil/power stage with a good used unit. The engine started instantly. I also changed the plug wires, for good measure.

Thank you for pointing me towards the coil!

Stay well!!!

Yours faithfully,

Spook

When my newly aquired CPS first showed some problem last time, it happened when the car was going thru speed bumps. The engine died. I was using Airtex. Trouble showed in less than a month of using. Luckily able to start again after the bump. Back home I reinstalled the old OE CPS with torn cable sheath repaired with electrical tape.

Maybe you could try putting back the old one?

Regards,
Amarin.

Dear Amarin,

Hope you're well. Thank you, for your guidance. I swapped-out the coil/power-stage with a known-good used unit. The engine at once started!

I moved for dismissal of the indictment against the crank position sensor.

Enjoy the weekend and stay well!!!!

Yours faithfully,

Spook

Thanks for the update my Dear Spook,

Regina coils issues has been here now and then. Any effective preventive measure against it? Something like yearly spring cleaning the contacts? What do you think? Mine has a Bosch system with the ignition module/ignition amplifier that seems to be its Archilles heel. Periodical renewing the heat paste/zinc-oxide compound has been proven to be effective.

In retrospec the newly replaced CPS should lasts its intended lifetime (about 5 to 10 years and maybe more) seeing that you've taken great care to choose Bougicord over aftermarket alternatives.

Having stock of known good spares is the proven backup plan for these cars, Regina and Bosch.


Stay well Spook!
Stay well Everybody!

Amarin.

Hi Amarin. When you're wrapping a damaged CPS cable, even better to use a wrap of aluminum foil under the electrical tape to act as a signal shield, preferably with the foil touching exposed braid. Aluminum foil duct tape is an alternative I've heard of people using, but you won't get the electrical contact to the braid (you could in theory run a ground wire to the foil, but I can't imagine anyone doing that)
--
Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now

Dear Dave and Amarin,

Hope you're well and stay so. Rather than electrical tape - which will dry-out/embrittle with time/heat - see if you can get a roll of butyl rubber tape.

Butyl tape - black or gray - is used by glass-installers because it does not harden with time/heat. That long-term flexibility means that when used to seal a windshield, the tape will stand-up to repeated heating/cooling cycles.

Best of all, when over-lapped and finger-compressed, the tape forms a solid mass. So, it enables you to place an impermeable but flexible boot over the point where the harness enters the crank sensor connector's housing. This joint is the usual failure point.

Hope this helps.

Yours faithfully,

Spook

I used aluminum heat tape that I got from Home depot,,I wrapped it around,,& car started right up,,

Hi Spooky Jay,

A bit disappointing having a relatively new CPS fail on you like that. Sure smells like it may be the problem. Genuine Volvo or aftermarket? I'm sure you'll be doing a visual inspection and double checking the firewall connector as well as making sure it's properly seated in the bellhousing. Are the standoff clips still in place to keep it away from the heater return line and to prevent cable flexing down at the sensor base? If needed, you can fashion your own standoffs using a stub of small diameter rubber hose and running a zip tie through it in a loop (quality black UV ties last longer, fatter the better, wrap the cable in a bit of electrical tape for added protection from sharp edges).

I can't imagine how the 2-2-3 missing IAC signal is related. Be sure to clear the code in case it's a spurious condition. A bad IAC shouldn't cause a no-start (your foot may need to be on the gas a bit, though). Note that the IAC is fuel side whereas the CPS is primarily ignition side with an rpm signal being passed to the ECU from the ICU. Apart from the obvious checking the connector on the back of the IAC, I see in the Pocket Data Book where you should be able to see a resistance through the IAC coil of approx 4 Ohms, if not then the IAC is definitely faulty. Note that this only applies to the 2-wire VDO IAC valves used in Regina, not the 3-wire Bosch ones used with LH. Taking a quick look at the online supply houses, they appear to be made of expensive Unobtainium. The Volvo ones are discontinued and I don't see any aftermarket, mostly just used on eBay.

You have my sympathy having to flat deck it home. A moment of shame when the neighbours see your cherished old Swedish iron coming home that way, a bit like you coming home in an ambulance. I've considered asking for late night delivery and no flashing lights, flat deck I mean.

Good luck!
--
Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now

Dear Dave Stevens,

Hope you're well. Thank you for the sage advice!

I swapped-out the ignition coil/power stage with a known-good used unit. The engine at once fired-up. I changed the plug wires for good measure.

I truly appreciate your help!!

Stay well!!!!

Yours faithfully,

Spook

Dear Dave Steven,

Hope you're well and stay so! Thank you, for confirming that the CPS likely is the culprit!! The failed unit was Bougicord, so from the OEM supplier.

As to the idle air control valave ( IACV), the car idled properly, so I don't know why the code was set. In any event, I have spare, "known good" VDO IACVs, which have been stored in climate-controlled, low-humidity.

I'm blessed with ideal neighbours - kind and helpful - so expect only "tea and sympathy".

Thanks again for your help!

Yours faithfully,

Spook

Spook,

I just spent at least 20 minutes trying to find a post either here or on tbricks that mentions the Regina tach bounce is not a reliable indicator. It may have even been in the faq somewhere. Admittedly I've read threads from guys with a Regina system that have seen tach movement. But I would put a $20 bill that in the last week I read somewhere that a Regina tach doesn't move until the engine starts, then it comes alive.

I say this because I have been troubleshooting my 92 740 w/Regina for some intermittent issues. I can attest to the fact that for mine at least, the tach never moves until it starts. This includes when it starts normally and has no issues. While your cps could indeed be suspect, I wanted to add this so you don't declare the problem solved based on the tach movement (or lack thereof) alone.

I too have recently replaced my cps with a Bougicord and that seemed to solve my issues for a few weeks. They then came back and I've since replaced the ignition module and coil, reflowed the fi/fuel pump relay, and replaced the ignition switch. The problem hasn't come back yet but as its only been a week, I'm far from declaring it solved. If you replace the cps and it solves it please report back. I may need to carry a spare in the trunk if it seems like we have a dud batch.

Dear nyalex,

Hope you're well. Turned out the ignition coil/power stage had given its all. I replaced with a known-good used unit and the engine fired-up instantly.

Thanks for your helpful guidance!!

Stay Well!!!

Yours faithfully,

Spook

You're correct. There is an entire ignition system (Rex) between the CPS and the coil primary where the tach is connected, so lack of tach bounce, which may or may not occur at cranking speeds, is twofold not a certain indictment of the crank sensor. Although it may correlate in many anecdotes, that's only because it is a part that fails easily and often regardless of age. Troubleshooting by other means besides part replacement may be the better approach.
--
Art Benstein near Baltimore

"People that can use a test light, meter, a scope, and talk to the consumer without being mean to them can do very well in this growing industry. I've been an
electronics tech for 30 years so I know just how much fun this electronic stuff is." -Dave dl242gt

Dear Art Benstein,

Hope you're well and stay so! Thank you, for your explanation. If the Crank Position Sensor (CPS) isn't the cause of the "no start", what's your best guess as to the cause?

The distributor cap, rotor, plugs, and plug wires were changed about 20K ago. The coil and power stage were replaced, when I last replaced the CPS (1K ago).

A point I omitted: when the car "died", I was on the way home after having had welded-shut a down-pipe leak. The car started as usual and ran for a mile or so. Thus, I doubt the welding did any damage.

Thanks again for sharing your insights.

Yours faithfully,

Spook

Hi Spook,

I agree with you about the welding. Any electrical damage from arc welding would have manifested immediately. However, work of any kind has the potential of physical change, such as a loosened wire connection, so a visual inspection of that work might be worth the time.

"If the Crank Position Sensor (CPS) isn't the cause of the "no start", what's your best guess as to the cause?"

Guessing is only useful if done by the well-experienced. My experience with Rex doesn't go beyond the usual corrosion trouble at the power stage and coil terminals, and that one event goes back almost twenty years for me.

Troubleshooting an electrical system is a matter of dividing the system into its functional blocks, making sure each has the power and input it requires to perform its function.

Otherwise we wiggle connectors and change parts 'til it works again.

Sorry,

Take care of yourself and good luck with the car.


--
Art Benstein near Baltimore

"If you can't fix it with a hammer, you have an electrical problem." -vwbusman66

Dear Art Benstein,

Hope you're well. I replaced the ignition coil/power stage with a known-good used unit. The engine at once started. I decided to change the plug wires, as they had seven years / 20K miles service.

Thanks for your helpful comments!

Stay Well!!!!

Yours faithfully,

Spook