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barbar1129 · 11-21-2010, 11:22 AM

The Check Engine Light keeps on coming on and off on my 1999 37V Discovery. I took it in to Cummins for a diagnostic check and I was told that the fault code was directed at the Position sensor either the position sensor was faulty , the wiring to the sensor , or the tone ring. I replaced the postion sensor and now the problem is worse. The CEL comes on more often, stays on longer and the engine rpms go up and then back down erratically. The engine is an isb 275 hp.

Any body else have a similar problem - if so , what was your solution ?

Thanks in advance for any help on this issue !

greystroke · 11-21-2010, 11:38 AM

Welcome to the Forum

I have an ISB275 on mine and it would be nice if you knew what codes the engine is throwing. Cuts down on the guesswork. I run the VMSpc on mine so if throughs a code I will know it. Then I go to my tables to determine the problems.

I am sure some experts will be along to help you soon. If you are close to someone with a code reader such as the VMSpc that can read your codes it would sure help.

barbar1129 · 11-21-2010, 01:45 PM

Okay - I connected my Discovery 37V isb 275 to VMSpc and the diagnostics came back with " PID 190 2 Engine Speed High Reading "

Searching on the net for PID 190 2 , I came up with four causes
http://www.heavydutypowertrain.com/md200codes.pdf Mid 128 Cummins
190 0 234 Engine Speed Greater than 2630 RPM
2 115 Loss of Engine RPM Signal
369 Fuel Pump Control Module
689 Engine Speed
2321 Engine Speed
Further research shows:
115 Engine Speed Sensor ESS Circuit
369 VP44 Fuel Pump To Engine Synchronization Pulse Not Recognized

When I had the diagnostic check done at cummins , they said it was related to the Position sensor and reading their invoice it shows the problem as " FC for 115 active EPS ..also shows overspeed 5600 rpm " . As stated earlier , I replaced the position sensor ( cummins old part #4002064, replacement part #4921597 ) and now the problem is even worse than before ! Any suggestions would be appreciated !

greystroke · 11-21-2010, 03:11 PM

Thanks for posting the codes.

Since no expert has checked in yet I will through a few things out there.

If you check the internet much on the ISB you will find that The VP44 and the lift pump have been troublesome. Remember back then we were not using USLD so without additives there could be premature failure.

Also in my readings the VP44 is cooled by fuel flow as it returns fuel to the tank. If the lift pump is not puttting out it could cause problem with the VP44.

If it were me I would check fuel flow out of the lift pump. I have read about two low readings 5 or 8 psi. If you have above 8 then the lift pump is probably ok. As I understand the engine will run even if the pressure is low.

Hopefully someone wil come to the rescue. I am still learning about the engine.

My guess it is a fuel problem.

Triker56 · 11-22-2010, 12:03 PM

My ISB with VMSpc has given me a.
PID 190 2 Engine Speed---Invalid Data
Since 2008. Cummins shop told me there it could be one of 3 different speed sensors from that fault code.

They ordered one that the tech said was it.
The sensor never came in the next day and I left the area.
I didn't get the part number they ordered.

It brings the check light on usually only once every day for a few seconds. Doesn't seem to cause any problem.

A year ago it was in the Coach Care shop to put a new fuel pump in with the low pressure light kit. I ask them to check the PID 190 out.
They did a reflash of the ECM and told me no code 190 was found.

After I left the shop, a couple hundred miles down the road the check engine light came on. VMSpc had the PID 190.

Engine still runs fine so far. I do carry ERS.

barbar1129 · 11-27-2010, 08:45 PM

I replaced the Speed Sensor ( Old part # 4002066, new part # 4921601). The check engine light no longer comes on !
I guess both sensors had to be replaced .

greystroke · 11-27-2010, 09:39 PM

Thanks for getting back. Useful information.

Triker56 · 11-28-2010, 06:12 AM

Could you give us a hint where each of the 2 sensors numbers are located at on the engine. Maybe even pictures?
Thanks

barbar1129 · 11-29-2010, 09:32 AM

I have tried to attach a pdf with picture and info !
Please let me know if you cannot open the pdf !

greystroke · 11-29-2010, 10:18 AM

Worked fine for me.

I assume you got the pix off quickserve. I get different info when I put my sn in. The list does not call the speed sensor as it you diagram. Mine has "two position sensors" instead.

At least we know what to do for a 190

So it is probably better to replace the speed sensor first.