The happy CEM story update

deano1 · Post by **deano1** » 11 Aug 2022, 18:27

I was having intermittent no start after running my 2002 S60 base so I tracked it down to no fuel pump activation after a long drive or when hot.
I noticed other members having similar issues with CEM after it get warm. Most diagnostic procedures say to warm CEM with a hair drier to re create hot CEM failure. Xemodex describes this procedure as well.
So before condemning CEM and paying the big dollars for repair I thought I'd do a little troubleshooting. First off I connected to VIDA and noticed I could turn the fuel pump at will.
Now I don't really know exactly how VIDA and Volvo cars interact but is seemed to me if i could turn on the fuel pump at will then the fuel pump simply wasn't getting signal to turn on when the car was hot and sure enough when I disconnected VIDA when the car was hot sure enough it would't restart.
Logically I thought there may be a corrosion issue in the harness between the CEM and the pump. After inspecting that connection definitely could not see anything by naked eye , but just in case I used a contact cleaner and a product named Stabilant 22 https://www.stabilant.com/ on the main CEM connection pins to the harness plugs into and connects to car.
Apparently this stuff is able to fill voids in male/female pin connections and creates solder like joints but remains fluid so you still have a reusable connection. Read up on this stuff!
After reconnecting everything of course the car started but it always did when it was cold but now it was time to heat this sucker up so turn up the floor heat to MAX and drive around,,,not much fun on 30*C day but this had to be done.
So far things are going well with not a restart failure to report.
But just for a back up plan I located the fuel pump relay and soldered in jumper switch just in case everything goes wrong.

: CeM1.jpg (190.15 KiB) Viewed 1023 times

Cheers Dean

Post by **erikv11** » 11 Aug 2022, 21:41

Please update about the stability of this fix over time. Great post!

deano1 · Post by **deano1** » 06 Sep 2022, 17:13

After about a month of driving, so approximately 1000 miles,, the dreaded hot no restart returned. I guess removing and cleaning CEM module pins was just a band aid solution.
But just going to say lucky thing I put in the jumper on the relay for the fuel pump circuit because this time when I felt the car wanted to stall from lack of fuel pressure after restart I just reached down a hit the toggle and ShaZam! engine came back to life. Fuel pump was back in the game.
And funny enough I was able to return the switch back to the off position once the circuit was complete?? Explain that one.
Seems the CEM is definitely weak but once circuit is complete then all is good because I've never experienced a stall situation while driving. It's either the fuel pump is engaged or it's not during the engine start up routine.
cheers Dean

Post by **br0dy519** » 07 Sep 2022, 19:50

Requesting mods change title to "unhappy story" ...

sorry it was too easy... good luck deano I believe you probably need to bring in the experts to fix that CEM

deano1 · Post by **deano1** » 08 Sep 2022, 15:42

Yeah you're right Brody, I'm sure the CEM will need a re build if things get any worse and I totally expect it will but til then I'll be using the 'ole toggle switch when needed.
Like today, I made a stop after work and sure enough it happened again but just did the toggle trick and I get home on time. Not sure how long this luck is gonna last but just so people know to keep a jumper wire in your glove box in case.
Yes you should be familiar with relay location.
Let's see now, how could I re tittle this and save a bit of face?
"The strange CEM story?" NO, or "Lucky CEM story?" NO,,
Wait! I Got IT!
"This is gonna cost me $500bux CEM story?",,, yeah eventually

Post by **jonesg** » 09 Sep 2022, 00:28

deano1 wrote: ↑08 Sep 2022, 15:42 Yeah you're right Brody, I'm sure the CEM will need a re build if things get any worse and I totally expect it will but til then I'll be using the 'ole toggle switch when needed.
Like today, I made a stop after work and sure enough it happened again but just did the toggle trick and I get home on time. Not sure how long this luck is gonna last but just so people know to keep a jumper wire in your glove box in case.
Yes you should be familiar with relay location.
Let's see now, how could I re tittle this and save a bit of face?
"The strange CEM story?" NO, or "Lucky CEM story?" NO,,
Wait! I Got IT!
"This is gonna cost me $500bux CEM story?",,, yeah eventually

your 3 weeks of summer will be over in a couple of days, or try a little cooling fan on the cem.

deano1 · Post by **deano1** » 18 Sep 2022, 14:07

The ole CEM did it's little trick again today on a 300 mile journey back from my parent's place. Was getting hungry so i figured I better stop for a little PopEye's and I knew conditions were ripe for a no start.
So all finished I jumped back in the car, twisted the key and it always fires but then it continued to stumble and stall. Okay some what prepared for this situation I toggled the fuel pump and tried again and away she went. Happy trails for me

I'll continue to update this until I have a complete failure I guess.
Now I'm wondering if I can do this same set up with my wife's V70 rear wiper? Appears like we have a REM problem there??
Cheers!

The happy CEM story *update*