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1998 v70 ECT connector failure Topic is solved

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1998 v70 ECT connector failure  Topic is solved

Post by sleddriver » Tue May 17, 2016 2:15 pm

After 18yrs, the original ECT failed this past Jan., causing the engine to be hard to start and the radiator fan to run in 55°F! Found one at a local CarQuest that was stamped "Volvo" and "Made in Germany" inside of a Beck-Arnely box for $27.

Now, this one is Toes Up. Radiator fan running when key is out, cold start RPM jumps to 2000, then drops. The code pulled was EFI-123,Intermittent, ECT Signal Too High P0118. Fortunately, it has a one yr. warranty. I spoke to my indy about this. He said he went through 2 or 3 on a car, including out of a Volvo box, before he found a good one. One was dead right of the box.

WTH is going on here?

Anyone else noticed this?


1998 V70 T5 226,808 miles. Original Owner.
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Re: Anyone Notice Repeated ECT Failures?

Post by abscate » Tue May 17, 2016 2:50 pm

Box or part stamped??

There is so much counterfeit crap out there, I'm not surprised


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Re: Anyone Notice Repeated ECT Failures?

Post by sleddriver » Wed May 18, 2016 11:16 am

The ECT itself was stamped. I looked back over my notes and noticed I previously had an issue with an "intermittent" signal. I cleaned up the connector, reassembled and it's lasted a few months. But now the gremlin is back!

I made some cold measurements yesterday and rechecked the wiring. I noticed the wires to the female sockets are untinned, corroded and stranded. Further, pushing the connector home I suspect, causes the female ends to move backwards in the housing, resulting in a poor contact. This could explain the "intermittent" flag. This sensor wiring has lived a hard, hot life being so close to the intake manifold.

I'm going to check the temp reading through OBDII and see if it makes sense. I'll also short the two female ends together which will indicate zero resistance to the ECU and max temp (250°F I've read) I'll look to see if the scanner will note this, then shake the connector and see if the signal drops out. If so, I'll rewire the female side using tinned, stranded wire insulated with Teflon (no more corrosion worries). I also have some solid tinned small gauge wire insulated with either Tefzel or Kynar that would also stand up to the heat.

There's a reason all marine-rated wire is tinned!


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Re: Anyone Notice Repeated ECT Failures?

Post by misha » Wed May 18, 2016 2:22 pm

That ECT could be for later v70,from 2001 and after.

Reading the post more carefully...i would say that problem is in corroded connector...just like you mentioned.
If the problem vanish for a while after cleaning it...that's it.Clean it and SEAT it properly and you're done.


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Re: Anyone Notice Repeated ECT Failures?

Post by sleddriver » Wed May 18, 2016 5:48 pm

UPDATE:

It was the connector. Plugged in the Autodiagnos scanner, read an appropriate hot coolant temp (97°C), then opened the hood & tapped the ECT connector and the RPMs immediately shot up, the cooling fan came on and the same code was set. The ECT reading at the time of event was -44°C, indicating infinite resistance because the connection was broken (OPEN) for longer than 0.5sec.

Cleared the code and repeated. Same result.

So I'll be rebuilding this short wiring harness. That will put an end to it.


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Re: 1998 V70 ECT connector failure

Post by sleddriver » Sun Jun 12, 2016 11:45 am

Update II:
I rebuilt the chassis-side connector & wiring yesterday as I began experiencing repeated CELs for the ECT signal being "too High" (open). Further, this sensor is very important to how the car runs, gas mileage, dash temp control, electric radiator fan control, etc. It's the only temp sensor the ECU has, so when the connection is knakered, performance suffers.

I started by draining the PS reservoir, then removing the RETURN hose to have more room. Next, I loosened the upper radiator hose clamps just enough to rotate the hose 90° CCW.

Next, I unplugged the ECT connector and cut the wiring harness about 4" away. The internal barrel connectors can be removed by prying down on the back of the connector, then sliding them out. The tiny, non-tinned wires were green & gummy with corrosion and deteriorated vinyl wire insulation. The consequence of living for 18yrs in such close proximity to the hot engine. I cut back to healthy copper.

The inner rubber/plastic barrel insulators inside the outer plastic shell had completely deteriorated and turned gummy themselves. This also wound up inside the barels adding insulation where none should be. If you look at the male end of the ECT connector, you'll note they may only be 5/16". Not much to go on.

I cleaned the goo off with denatured ethanol, used a wire wheel in a Moto-Tool to remove the corrosion on the outside and ran a small cone brush inside to get rid of the goo. Then followed up with a rolled up piece of 320g sandpaper to remove the corrosion inside the barrel.

I cut the frail wires even with the connector and cleaned it well. Next I used some Teflon insulated, tinned aircraft wire I happened to have on hand to replace the old wiring. Instead of soldering these two, I decided to wrap it with fine wire first to hold it into place mechanically and make a better connection since I was just going to be laying the new wire on top of the old crimp, holding both in place using one of those "extra hand" devices with two alligator clips. I tried taking a picture, but my borrowed camera won't focus that close.

I first tried a solid wire from a CAT5 cable, but then went with very fine 30ga I think wire-wrap wire with the insulation removed. This worked out well, made a strong joint and the solder nicely flowed out on the cleaned brass barrel connector. Lastly, I slipped a piece of heat-shrink over both the brass barrel, solder joint and about 2" of the new wiring and shrunk it into place. With tinned wiring, it won't corrode and the Teflon is well up to dealing with the heat. These new "pigtails" also had some extra length so I could re-route the wiring away from any contact with the intake manifold and make access to the connector easier.

Back at the car, I slipped a piece of HS over each end, then twisted them together and soldered. It's a bit tight down there, especially with big hands.

I popped the male ends out of their outer shell and wiped them down with ethanol to be sure they were free of the goo. All told it looks like this:
006.JPG
The final step was to slide the outer shell back onto the male end to shield the joint, hang the wiring from the upper radiator hose with a zip tie, connect & refill the PS reservoir and return the URH to its normal position.

As I'd previously disconnected the battery to clear the code, I was now ready for a test drive. No more CEL nor faulty, intermittent ECT wiring.
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Re: 1998 V70 ECT connector failure

Post by BEJinFbk » Sun Jun 12, 2016 2:19 pm

It's not heat that causes that green corrosion and black crap in the copper - It's moisture.
That's why a good solder joint and heat shrink tubing with the adhesive sealant lining lasts
so well under the hood and with other exterior splices. And to avoid leads failing from metal
fatigue, you should really go with a stranded wire instead of solid. There's a reason that you
never see solid wire in applications where the wire is exposed to vibration.

There's also a shorter way around those corroded connector contacts. Something a little easier,
faster and much more durable in the long run would be replacing the failed connection with a
new OEM weather tight connecter using stranded hook up wire designed for automotive use for
your extension. You can still get contacts and plug bodies from Volvo and keep it all stock.

Yeah, you'll need the right crimper to apply the open barrel contacts, and tinning them after you
crimp'em will help prevent oxidizing, but protecting the contacts from moisture is the main goal.
Ranging from this:
http://www.ebay.com/itm/Excellent-Molex ... SwYmZXIZPK

To the good stuff, if you do this kind of thing a lot:
http://www.ebay.com/itm/Sargent-Tools-H ... Sw-zxWn5dA
( BTW - This is a screaming deal for a ratcheting crimper - These usually cost 200-300 bucks! )

Keeping it OEM is just a personal preference, but to me - Totally worth it down the line.
You can extend the car side harness with a short length of the appropriate wire and then
solder and shrink the splice. You should never have to mess with it again.

If you can't stand parting with money at the dealer, here's an example of another option for a clean install:

http://www.ebay.com/itm/WEATHER-TIGHT-P ... bw&vxp=mtr

Crimp the female contact side to the car side harness and a long pigtail of the stranded wire
to the male side ( Leave plenty of length for any future ECT swaps ). It still takes the right
crimper, but hey - Water Tight Connector! With the long leads on the sensor side of the new connector,
you can solder and shrink the new pigtail to the ECT out of the car and save yourself a little hassle.

One more weather tight connector option, just go with a "pre-terminated" connector cut out
of a doner rig at the J/Y and solder and shrink both sides. Not my favorite, but relatively
cheap for water-tightness.


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Re: 1998 V70 ECT connector failure

Post by sleddriver » Mon Jun 13, 2016 1:36 pm

Vinyl insulated wire only lasts so long in a hot environment, particularly in an engine compartment, in Central Tx. Ozone will also degrade it over time. As I type, it's 92°F, 68% Rh, and the solar heat index is 130°F. Once the vinyl starts breaking down, moisture + oxygen gets to the untinned copper, oxidizing it.

Not sure why you think I replaced stranded wire with solid, as the or/wht wire in the photo is stranded. Also, not sure why you think auto hook up wire is better than aircraft wire. Marine wire would be an upgrade as it's always tinned, but still suffers from cheap vinyl insulation. I found it very odd that the ECT pigtail wiring is larger gauge than the other side, which is rather flimsy.

I wasn't aware these connectors are avail new from Volvo? How would I look them up?

I do own a professional ratcheting crimp frame with interchangeable dies and an assortment of crimp connectors, both insulated & non. However twist & solder here was the preferred choice. A barrel wouldn't work due to the difference in wire gauges.

All contacts were thoroughly cleaned with ETOH and treated with Deoxit Red before assembly.

J/Y connectors don't really make sense to me for an old car, as they'll also be old, exposed to heat, moisture, oxygen, ozone & rain. So will any wire attached to them.

This fix will outlast the vehicle, no doubt.


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Re: 1998 V70 ECT connector failure

Post by scot850 » Mon Jun 13, 2016 7:40 pm

Well done and being persistent appears to have worked for you!

Neil.


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Re: 1998 V70 ECT connector failure

Post by sleddriver » Mon Jun 13, 2016 7:56 pm

Thanks Scot!

Wish I had some of your cool Canadian air down here....it's just brutal.


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